I had an Aerocruz 100 in my Cherokee 235. It’s a fine little autopilot - will only fly heading mode (when coupled to an appropriate source such as a G5), track mode using its INTERNAL GPS, or GPSS mode when coupled to a GPS navigator. It will not fly an ILS approach or anything other than GPS. It’s is NOT certified for coupled approaches (although as mentioned it will perform that task - just not legal). BK Aerocruz has no auto trim (it does on the experimental version), and you’re constantly retrimming. It had difficulties tracking in anything greater than light turbulence. Having said that, it is a perfect little unit that does the job at a reasonable price.
I have a GFC-500 in my O. You cannot really compare the two autopilots. The GFC-500 is a full featured autopilot, will fly just about any approach you can find, has VNAV and a whole range of advanced features.
If GPS is spoofed or jammed, neither autopilot will be able to function with its full feature set.
It’s really just a question of budget. If you have the budget and are willing to spend it for the GFC-500 then that is clearly the best autopilot in terms of features, etc. If you have a smaller budget, then Aerocruz 100 is a good choice that you will be happy with. Just know what the capabilities are so you are not disappointed.
Garmin replaced the servos in my O 3 years ago and they have worked beautifully ever since with no issues whatsoever.