I think 1 owner and never messed with is really important. Same thing with my 980... well, I'm the third owner (so it was 2 before me), but similar.
I've always used Aero Air for my avionics work. I don't know that they're the "best" by any means, but they've done well for me. They even did the GTN625/ADS-B installation on my Citabria. I was a bit nervous about that one, because they really don't have experience with fabric airplanes, but in the end they were able to re-use the existing antenna locations (it had Garmin equipment from new), so the fabric wasn't an issue.
I guess what I would say about them is that they've generally done what I needed with fairly minimal issues, both on a major upgrade to the 980 and a moderate one in the Citabria. I believe the 980 took a bit longer than originally scheduled, but not bad in comparison to the horror stories you often hear (and I always take the quoted schedule with a grain of salt anyway).