If anyone wants to know how the TruTrak ADI works, there's a pretty good description in their patent 6,961,643 at the
www.uspto.gov site.
As I suspected, it works differently when you power it up on the bench than it will in flight, because the VSI didn't see a climb.
While it's true that accelerometers, rate gyros, etc. could have been used to make an AHRS, I doubt TruTrack could sell that for $1000 and make money. This seems like a neat little gizmo. It's well matched to how pilots will use it...it may not show "real" pitch and "real" roll, but I bet you could fly an instrument approach with it, which is what matters.