garry
So what is new in X3 Producer that would make me want to spend the $150? I've been known to suffer from GAS, especially when stuff is on sale, but X2 has been mostly flawless for me. I'm in the final stages of mixing our album, so if X3 has some whiz bang feature that will help those mixes, now is the time to upgrade. CD needs to be on its way to the plant by mid May...

Garry,
I was on the fence for a looong time before I upgraded. I got a special discount price that helped my decision a lot, but if I needed to spend $150 then I think I would have done it anyway. To me, the X3 features that I like the most are, besides about 10,000 bug fixes, the following:
 
1. Clearer, more colorful (plus contrasty) track view display.
2. Fly-out ProChannel EQ with built in equalizer. This is an awesome feature that should have been done long ago.
3. The included Blue Tube effects. The Gate works very well with my external hardware to cut out some noise floor issues. No other gate worked for me (i.e. Sonitus or freebies).
4. Track/bus color customization.  This does in fact help me keep organized in an otherwise ADD-world!
 
A bulk majority of my work is in both MIDI and bounced-down audio. I don't use VST synths much.  One of my favorite VST synths (Largo) has some issues with X3, unfortunately. Also, X2 projects working in X3 don't seem to play nice together.

2:43AM
Also, X2 projects working in X3 don't seem to play nice together.

 
Now that's a concern. I can finish the band's first CD in X2, but we have 8 more songs that are half-done already in X2. What kind of issues have you seen working on projects started in X2?

garry
Now that's a concern. I can finish the band's first CD in X2, but we have 8 more songs that are half-done already in X2. What kind of issues have you seen working on projects started in X2?

 
You know what, after thinking about it further, I suppose some of my X2 vs. X3 project issues have come from my plugins. There is also a count-in issue that STILL exists (for me) in X3 the same as it did in X2...and X2 projects in X3 exhibit the same behavior regardless. So I may have to retract that statement from my post. I think we should let others comment on this to be sure.

Duplicate post.

Hi,the stability of x3 is much better than x2 but have many problems here also.
Melodyne is good. I had x1 prod,x2 prod and x3 prod and i think that is the x3 is better . I use 20-30 channel per project with many vsti.( win7 64 bit)

I don't know that I'd upgrade mid-project with a looming deadline, but I WOULD at least purchase it, and install once the project is done.  It's been a huge upgrade from my standpoint.
(1) ProChannel EQ with flyout and visual - VERY helpful
(2) Comping far far far quicker and easier.
(3) Melodyne - worth the Sonar upgrade money alone.  Love it so much I bought the full version at the upgrade price, and THAT's been worth the money many times over.
(4) Addictive Drums.  Huge step up from Session Drummer/ etc.
(5) Blue Tubes effects.
Plus more.
Love it.
 
 

Yes you should.

I think most have covered it above, but upgrading from X2 Pro to X3 Pro was a good deal for me.  I think the major selling points of X3 Pro are:
- increased stability
- Melodyne essential integrated
- quad curve EQ flyout
- improved comping.
 
I think these were more than worth the upgrade price.
Russ
 

Suggestions:
You can buy it. I would recommend it for sure.
Install it along side X2. They can co-exist on the same PC.
Keep working on your project in X2.
Play with X3 in the mean time.
If no issues crop up, use X3 to finish your project.
 

If I was in the middle of a significant project, I would defer installation until after the project was completed. There are significant changes to plug-in management in X3. The plug-in manager and VST scanner are shared utilities used by all version of SONAR installed on the machine. While it should not be a problem, why risk it?