I installed the TruTrak AP (Gemini controller version, non-certified; it's the one with a flight instrument style display) in my Northstar, a Supercub lookalike.
[SKIP TO PARAGRAPH THAT STARTS "BOTTOM LINE" if you aren't interested in details!]
Installation of the pitch servo on bottom of floorboard under pilot seat was reasonably straightforward. The cable on the servo wraps about three turns around a capstan and the cable then attaches to the elevator control cable with aluminum clamping bars.
The roll servo was more of a challenge; I couldn't find a straight run of aileron control cable where I could mount the servo. Final solution was to mount it facing forward under the passenger seat with the capstan just ahead of the passenger seat forward bar. The cable on the capstan then went outboard on both sides and around pulleys that I installed just under that seat bar and attached to a swiveling bracket I built that attached to the rear seat control column. So the rotary motion of the servo translates into pulling right/left on the control column.
There was a fair bit of wiring and soldering to the three connectors (two servos and the controller); only solder-tail connectors were provided. If I were to do it again, I'd buy connectors with individual crimp pins (B&C).
The pitch servo worked great from the start. The roll servo never did. I spent A LOT of time ringing out my wiring, removing and reinstalling the roll servo, and even sent it back to TruTrak (they said it checked out fine!). Lots of time on phone with a technician at TruTrak. Finally he suggested attaching the roll servo connector to the pitch servo and voila! The roll inputs to the pitch servo drove it great in both directions. So it seemed obvious that the roll servo wasn't working; I sent it back down there and again it checked out fine.
Finally I took the plane down to the TruTrak factory in Arkansas (foul weather). The problem turned out to be inside the controller and required some bench work to fix it while I waited. Both servos were working great now! I discovered that I had a baud rate mismatch between my Garmin 496 and the TruTrak; when that was resolved, the AP worked exactly as advertised. I still have to tweak a couple of parameters because it overcorrects when tracking to the course set in the Garmin, but that can be done in the air easily. The pitch servo and altitude modes (hold, climb, descend) work great as they always have.
BOTTOM LINE: I like the TruTrak, and the people at the factory were very responsive and helpful. Maybe the controller problem should have been found and fixed before it was shipped to me, but maybe a solder bridge I discovered in my rework had damaged it. Whatever, TruTrak is a known entity for me now, and I plan to put one in my 180 when they get their STC. I like that the 180 version doesn't use control cable attachments; it directly drives bellcranks using push/pull tubes.