Narrowed it down for an interface....your opinions...?

If it was me (tho I haven't used either unit) I go w/ USB.  Firewire will only get more difficult to accomodate (note, I use FW).
 
@

That is my thoughts too AT.  I'm pretty confident that USB will be around for a few more years.
 
I too still use some FW connectivity.  My Sony HVR Z7U video camera uses the CF recorder which uses FW to transfer the video files.
 
Both of the Focusrite units look good...both cosmetically and specs.  But my final choice is one I will need to live with for at least a couple of years to get my money's worth. (yeah...I'm kinda frugal) :) .

I'm also surprised that these units are not USB 3.0.  I built my computer over two years ago and my MB has 3.0 .
 
I don't know that I've seen an audio interface that is 3.0 .  That doesn't mean there isn't one...but I haven't seen one yet.

I would say USB is more likely to be around for longer, however Focusrite state that all their firewire units are Thunderbolt compatible (with an adaptor, but with no loss/gain in performance).  I'm now using a MacBook which has two usb and 1 firewire port, so I'm going to get myself the Saffire PRO 24 DSP for mobile use, as it still leaves me a usb port each for a controller keyboard and Maschine.
Andy

It all comes down to drivers, drivers, drivers!
Check the RME website for some info on USB vs FW. http://www.rme-audio.de/forum/viewforum.php?id=4
RME is convinced that USB is faster (on MOST systems), seems there is a "hidden" 32 sample delay using FW; I think that's right.
Remember MS "broke" the FW drivers in Win7, and changed it again in Win8.
I'm running the UFX via USB and my FW-1884 (control only) via FW; just a matter of time with the 1884; sad really...
Unless something has changed recently (or is about to), there are no USB3 audio interfaces.
HTH,
Tom

Rme has some usb 3 interfaces . I tried the second focusrite you mentioned for a month. I adored the sound but had fire wire issues in my laptop. Ti card. So I returned it and eventually got the rme. The rme is cool and is more transparent than the focusrite, but do love it and use the related software ALL THE Time. I watch TV monitoring the spectral analyzer et al. My Ucx is not a usb three device, but it has usb3 drivers and works fine on usb3 ports.

When say more transparent I mean it didn't have the liquid pres . Those liquid Pres are awesome.

You won't notice a difference in performance between a USB2 audio interface vs. Firewire.
The best USB2 units offer low round-trip latency... right on par (a little better in some cases) than the best Firewire units.
ie:  The RME units yield 4.9ms total round-trip latency at a 48-sample ASIO buffer size/44.1k
 
You previously asked about the FastTrack Ultra 8R.
That unit is actually pretty decent.
I shelved mine for a good while (when they removed "high-performance" mode - which offers low round-trip latency).
With the latest driver update (recent), high-performance mode is now back.
Round-trip latency is 5ms at a 64-sample ASIO buffer size/44.1k.
The analog section is just a little bit bright (compared to some units), but you can capture good results with it.
If you can source one for under $300, I'd definitely consider it.
I used mine playing soft-synths live (64-sample ASIO buffer size/44.1k) using Forte' as a host.  Never a single glitch...
 
The Focusrite units offer ever so slightly better fidelity.
The M-Audio unit offers lower round-trip latency.
 
If you go with a new Focusrite unit, I'd opt for USB2 over Firewire.
Firewire isn't going to immediately disappear... but it's nowhere near as common as USB2.
Again, there's no performance gain going with Firewire, so you may as well get the unit with the longest shelf-life.
 
If you get a Firewire unit, you'll want to use a PCIe TI chipset Firewire controller.
That eliminates most compatibility issues... and ensures maximum performance.
Certain Firewire units are *very* particular/finicky about the specific TI chipset controller (ie: Mackie and Tascam).  

AT
As Jim et al says above, FW will be around on pci cards etc. but USB will be native.  Thunderbolt seems like thunderdud w/ the slow adoption rate, except on Macs.  Maybe if they lower the price?  $500 is more than a lot of computers these days.
 
But USB is fine for most jobs, USB 2 is fast enough for most recording, so I would go that way.  A bit safer, esp. if you plan on keeping the interface for a few years.
 
@

Thunderbolt is great... but when it's a $500 option for your audio interface (ie: Apollo) that's a serious consideration.
 
Thunderbolt external HDs are also extremely expensive.
USB3 enclosures top out at ~550MB/Sec (fast enough for most users - a little faster than a good SATA-III SSD).
ie:  A 3TB external Thunderbolt HD is ~$350.  The USB3 version is ~$130

Ted: go with firewire and Ti chipset card.. you will not have any issues !

Thanks so much folks...!!!  Some very valuable info here.
 
Jim,  I've seen a few different online sellers with the FastTrack Ultra 8R for $269 with free shipping.  That is a pretty good deal...I was just concerned about drivers, but have noticed on their website that they have fairly updated drivers...which is nice to know.
 
I like the Focusrite products simply because I like a product that has the power supply built in...ie it uses an IEC power cord plugged directly into the unit instead of using a wall wart.  Plus the fact that there are really good reviews about the preamps and included software (along with the fact that they include some Focusrite Plugins).
 
Now it's time to make a decision :) . 
 
Thanks again folks...!!!  You guys rock.

garrigus
..... I would think you'll still be able to add FireWire with a PCIe card even if it doesn't come on the mobo.
 
Scott

Completely agree with Scott, here.
 
Both of my two home-built desktop DAWs have PCIe FW add-on cards - each hosting a different model FW audio interface.  Short of the manufacturers dropping support for either of these devices, I expect to use them for years to come.
 

MaximumPC magazine said many issues ago that Firewire was dead. I would go with USB. 

When I was first considering a USB audio interface, I had concerns about bandwidth, too.  So I started doing the math.  What I learned, in a nutshell, is that in order to run out of USB bandwidth, you'd have to run like a gazillion simultaneous tracks.  Okay, maybe not a gazillion, but it was more than I could ever dream of using.  The only practical reason to consider Firewire was stability.  But USB has only gotten better, while Firewire has been left behind.  I think Windows 7 has really squashed any lingering USB issues.  So, any fears that USB 2.0 isn't fast enough are unfounded.  That's why it's become the "default" connection for modern audio cards.  It's also why USB 3.0 hasn't been widely adopted.  It simply isn't necessary for audio processing.
 
~ Heather

As you can see in my list I have been a very happy MOTU 24io user for many years. It is a PCI card based and it was a little cramped for synching with just word clock. I bought 2 Roland Studio Captures a couple of months ago and have had no problems what so ever. These things sound great and have very low latency. The only thing that I have had trouble with is having to reset the auto-shutdown when you first turn them on. I did notice when the computer shuts down it resets the unit back to the factory setting on the interfaces. I was informed that the Octa-Captures have the same issue. I won't go into the features here. Search for them on the Roland site. They are a little pricey but well worth it.