This is probably the best forum for feedback on anything experimental. Just don't mention your aircraft type (much) if it isn't an RV!
I'm flying behind my second TruTrak, and it is awesome.
My first was a DFC200, and I had two complaints. One was that if I ran it off the aircraft static system it would PIO. That was solved by simply using cabin air for the autopilot only (but that can cause it's own problem if you change vent or window settings and aren't expecting it). The other was a problem that is well documented now, but which I was one of the first to complain about - a tendency of the autopilot to either dive or climb (depending on whether you had the pitch reverse jumper installed) when you keyed the radio.
The static problem can be "solved" by using the smallest possible diameter static lines and using the "Static Lag" adjustment of the autopilot. However, I'll point out that even under ideal circumstances if you fly through rain you might get some bobbling as water droplets roll across the static port - so why bother? Cabin air is just fine for the autopilot.
The radio problem has also been resolved with a filter TruTrak now keeps in stock. They are investigating exactly which pin is the offending culprit so they can build the filter into their newer products. It only ever affected some airplanes, mostly of the fiberglass variety.
All of that said, I have my current Digiflight II VSGV linked to a Garmin GNS 480 (on the ARINC ports) and Garmin 496 (on the serial ports). It will fly a coupled precision GPS approach better than you can once you get the settings optimized for your airplane. It also can act as a redundant attitude system - if you get confused, just turn on the autopilot and set it to altitude hold.