I know the difference between the G5 and GI275 units and their respective high and low points, such as having to keep my vacuum AI with the G5’s to run autopilot, but looking for cost estimates only with interfaces with common equipment to the below: Piper Cherokee 180E Avidyne 440 Piper Autocontrol III S-TEC 60 PSS system If the price delta between the installs is too great, I’ll go G5 because I plan to upgrade my plane in the future. I’ll take shop recommendations as well.
When I got quotes for installing two G5s vs. two GI-275s, the difference in labor was in the noise. I only have a Century IIB (no vertical), so it could be there's a major difference when you factor in the S-TEC 60 PSS, but I doubt it. I went with the GI-275s so that I could pull the vacuum system and used a shop local to my airport in the Pacific Northwest. They did good work, but I wouldn't recommend flying from OKC for them. I really like the GI-275s. Especially now that they allow for an external physical switch to switch between heading and GPSS modes. It's a whole new autopilot now.
Dual G5s W/GAD11, GMU-29B Vac removal .411/.413 STC paperwork Remove ADF W&B Wire to GTN650 ADS-B already done thru -345 $11k
