I've been looking at the Zoom UAC-2 USB 3.0 recently, and I'm tempted by this device due to the quality converters inside and the advantage of the USB 3.0 speeds. 
 
Has anyone any experience with this device, particularly used with SONAR?

3 months in and I'm well pleased with this product. No issues whatsoever, well, once I got my head around the latency rules. Very easy to use, solid and up to now dependable.

Not many USB 3 interfaces out there (Only other one I know of is the one from Presonus).
 
It's nice to hear that it's working well well and stable with Sonar.  So, what kind of latencies are you seeing?

AlanSJackson
I've been looking at the Zoom UAC-2 USB 3.0 recently, and I'm tempted by this device due to the quality converters inside and the advantage of the USB 3.0 speeds. 
...

I'm struggling to understand why you think you need USB3 for a 2 input/2 output interface? I've got a 16 in/8 out, and USB2 has proven plenty fast. What advantages do you get that makes it worth an extra $50-$100? Heck, for another $50, you could get a Tascam US-16x08 (the US-20x20 with USB3 is another $250, for example).
 
I used to chase specs...in cars...
 
Damn, but I wasted a LOT of money on cars.

I can think of one area, especially if he works a lot with midi/soft synths -- low latencies.  Just like FW is faster than USB2, and PCI is faster than both, the result is (theoretically) lower latencies.  If you work mostly with audio, then you don't know what it means to have to freeze instruments during a heavy midi production. 
 
With lower latencies, it's less of an issue (or even a non-issue).... You keep piling on virtual instruments, and your system just handles it.
 
Based on the advertised latencies of these USB 3.0 units, that's one of their big strengths.
 
Added:  I just thought of another benefit to low latencies:  Hearing FX with live guitar playing.  I'm not a guitar player, but I've seen plenty of posts where others have considered this important.

JonD
I can think of one area, especially if he works a lot with midi/soft synths -- low latencies.  Just like FW is faster than USB2, and PCI is faster than both, the result is (theoretically) lower latencies.  If you work mostly with audio, then you don't know what it means to have to freeze instruments during a heavy midi production. 
 
With lower latencies, it's less of an issue (or even a non-issue).... You keep piling on virtual instruments, and your system just handles it.
 
Based on the advertised latencies of these USB 3.0 units, that's one of their big strengths.
 
Added:  I just thought of another benefit to low latencies:  Hearing FX with live guitar playing.  I'm not a guitar player, but I've seen plenty of posts where others have considered this important.

I have not seen these advertised latencies but it opens up my curiosity whenever I decided to upgrade my legacy audio devices.
 

I'm struggling to understand why you think you need USB3 for a 2 input/2 output interface? 

 
It's pretty straightforward really. I Upgraded my machine (laptop) which has USB 3.0 as standard on all 4 ports. When Win10 came in and destroyed everything, I ended up with the Zoom because every USB 2.0 device hated the USB 3.0 port and though they worked, they never really worked properly.
 
The reason I bought the Zoom was for the Burr-Brown converters, the built in up sampling and the simple interface. As someone has said, 2 in 1 out. It does have MIDI I/O which I've yet to use. Hi-Z, and the added advantage of having enough USB power for phantom mic's.  
 
I wasn't looking for 'go faster' stripes; just 'go'.