X3 for me is rock solid. X2 was a little flakey at first with a bug browsing audio files in the browser, but that was fixed in X2a. X1 was also rock solid for me.
 
Although I've never had much problem with drop outs I can't even provoke one now, and that's running my interface (ZED-R16) with as low latency as it'll go but A&H have updated their driver which I suspect is also partially the reason for that.

Generally X2a has been pretty stable for me. I've had the oddball event and experienced some of the more common things like having a crash when adjusting a bus a floating console view on a second monitor. Other than that I don't have any other "this will cause a crash" situations.
 
I bought the update this morning, went to work and mixed in X2a for about 4 hours and decided I would install X3 on my break and see how it would work in some tracking sessions I would be working on later this evening. I'm generally not into trying a new version in those circumstances. I had X1 unused for two months before I got through the backlog of projects started in 8.53. I opened the project in X3b with no funny business. It played and sounded like I expected. The projects are 96k with 13-14 drum mics, DI and mic'd bass and about 5-6 guitar parts that are always playing in some combination. The tracks aren't mixed but they all have some eq, compression and the odd effect here and there. It was super smooth tonight and generally a transparent experience as far as noticing any negatives. The new comping is so much more fantastic that I couldn't believe it has been done any other way. OMG, so good.
 
I haven't had a chance to open any older, more complex projects but I'll try it out soon enough. I love the new quad eq or whatever it's called. The larger graph and analyser seems so helpful that it almost made me suspicious for some reason. The one track where I used the tape emulation on the drum mix sounded much more punchy and crunchy in a good way than the second track we had up that I didn't have as much time to work with.
 
With X2a I really liked the console emulations over most of the other updates to the application but with X3 I'm digging the editing functionality and general performance more so than anything else at the moment. I'd say jump on it.

It is perfectly feasable to set your on-board sound as the default windows device and keep your pro device (the Scarlett) for Sonar. Simply de-select the onboard sound device within Sonar preferences.

Use tha ASIO drivers that came with the Scarlett, do not use Asio for All, IMHO its a disaster waiting to happen, especially if you already have decent Asio drivers.

Cheers,
Jerry

joakes
It is perfectly feasable to set your on-board sound as the default windows device and keep your pro device (the Scarlett) for Sonar. Simply de-select the onboard sound device within Sonar preferences.

Use tha ASIO drivers that came with the Scarlett, do not use Asio for All, IMHO its a disaster waiting to happen, especially if you already have decent Asio drivers.

Cheers,
Jerry

Woah - you've entirely missed the point of using ASIO4ALL.
 
You don't use ASIO4ALL to replace the ASIO drivers for Scarlett (or any other professional interface) you use it so that you have an Asio hook up to the WDM audio system on your laptop (or possibly desktop).  
 
I've got an older dual-core HP Pavilion laptop and without ASIO4ALL I can't use that laptop's built-in Audio with Sonar or any other DAW- and there are times when that's exactly what I need to do.  Using ASIO4ALL I can work with audio projects using my laptop while on a plane, at lunch in a restaurant, or any number of other circumstances where dragging along another piece of gear would be impractical or too cumbersome. 
 
 

Rock solid here.

TheSteven

joakes
It is perfectly feasable to set your on-board sound as the default windows device and keep your pro device (the Scarlett) for Sonar. Simply de-select the onboard sound device within Sonar preferences.

Use tha ASIO drivers that came with the Scarlett, do not use Asio for All, IMHO its a disaster waiting to happen, especially if you already have decent Asio drivers.

Cheers,
Jerry

Woah - you've entirely missed the point of using ASIO4ALL.
 
You don't use ASIO4ALL to replace the ASIO drivers for Scarlett (or any other professional interface) you use it so that you have an Asio hook up to the WDM audio system on your laptop (or possibly desktop).  
 
I've got an older dual-core HP Pavilion laptop and without ASIO4ALL I can't use that laptop's built-in Audio with Sonar or any other DAW- and there are times when that's exactly what I need to do.  Using ASIO4ALL I can work with audio projects using my laptop while on a plane, at lunch in a restaurant, or any number of other circumstances where dragging along another piece of gear would be impractical or too cumbersome. 
 
 

ASIO4ALL is working so well for me I've packed the scarlette away and using the notebook internal sound card... so much more simpler to use now.  I'm finally getting down to enjoying using sonar now.
 
cheers
Jim

X1 Rock solid / optimsed
X2 not rock solid / less optimsed (i passed)
X3 Solid (not as X1) / not optimsed ..
 
This is the way i feel it ....X3 engine is never near X1 
 
Features wise X3 is almost near what we draemt on (expet stuff weird here and there , and options they took off , i don't know why , that were here in X1 !!)

jscomposer

Fabio Rubato
It's fairly stable for me, although still getting blue screens when working with wave files...the more I work it, the higher probability it's going to happen. If I close and then load another project, it's usually not long before a problem occurs. I've since uninstalled and then re-installed in safe mode and am currently testing. 
 
Other than that, it's good. My Alchemy plug-in however asks me to locate its data every time I run a scan, which I do once on start-up. I'm not sure whether I need to do a scan every time though.

Fabio, sounds like you are you running XP? Win 7 or 8 would probably fix some of your issues.

Hey, JS...I'm running Win7 64bit - need to do my signature. 

TheSteven

Fabio Rubato
It's fairly stable for me, although still getting blue screens when working with wave files...the more I work it, the higher probability it's going to happen. If I close and then load another project, it's usually not long before a problem occurs. I've since uninstalled and then re-installed in safe mode and am currently testing. 
 
Other than that, it's good. My Alchemy plug-in however asks me to locate its data every time I run a scan, which I do once on start-up. I'm not sure whether I need to do a scan every time though.

Re: still getting blue screens when working with wave files..
Fabio are you mixing VST2 & VST3 Waves plug-ins in the same project?
The Waves VST2 & VST3 Shells are incompatible and can not be running within the same project.
It's been mentioned in other threads that its a known Waves issue that affects usage in ANY DAW.

Hi TheSteven. Yeah, I've seen this...initially a little confused as I've been aware of VST3 with Melodyne - have Ozone as well, but didn't know it was VST3. With X3, I can now run them as such...
 
It would seem from the above post that I can apparently mix VST2/3 if I do the following:
 
A mix of VST2 and VST3 Waves plugins can happen under the following scenarios:

• You have "Replace VST2 Plugins when opening projects" (under Edit > Preferences > File - VST Settings) turned off, open a project containing VST2 versions of Waves plugins and later add a VST3 Waves plugin
• You have "Hide Related VST2 Plugins" disabled (under Edit > Preferences > File - VST Settings) and open both VST2 and VST3 plugins

This would seem to suggest that as long as I have the 'hide related vst2 plugins' disabled, I am able to open both without it being a problem?
 
So do I have the first one - replace vst2 plugins... - turned off, along with the second one - hide... - disabled?
 
 
Irrespective, I've been getting these blue-screens for many years now...from Sonar 8 through to X3. I think it's my Creative drivers - for my Elite Pro. I've ordered a Roland Quad-Capture and see if my theory is correct. The Elite Pro's been the common denominator in all versions. 
 

Very solid. Just don't bring in any old X2 projects or you might feel different.