It's working fine here with X2 Essential, 32-bit.
I only have a few qualms with AlphaTrack...
1 - When switching from bus to track, the last track selected isn't highlighted until you actually rotate the knob for track selection. or press a the track selection button. However, all Alphatrack functions (knobs, fader..) do act on that track. This is a minor annoy - most likely an Alphatrack driver issue.
2 - No way to access bus pre-fade trim and pan, only post-fade pan.
3 - Values for trim and pan never arrive at true zero as seen in console. (it's using floating point internally..)
All of these are likely issues within the Alphatrack Sonar driver itself. I've built the control surface SDK sample to have a look see around, and it's a do-able job to writer a custom driver for AlphaTrack if I *really* feel like I want to. (I'm a SW Engineer..) The Alphatrack documentation is pretty straightforward.
Seems like Frontier Design is on hiatus or something, several of their products are no longer available from the biggies like zZounds or Sweetwater. (Heh, I noticed B&H closing out on X1-E at $49 - great deal especially with the upgrade to X2...)