@flavio81 You made my point: most camera service people are trained and experienced with mechanical work, while few (outside of factory-sponsored shops that work on only a single brand and hard cutoff service some set number of years after a model is discontinued) have useful levels of electronic skill. Further, as
@raizans pointed out, relatively new electronics with microcontrollers and firmware are less repairable than the older ones that have component-level electronics, even if your repairer has the skillset to troubleshoot and repair component electronics.
Furthermore, I have a personal history of repairing mechanical cameras, starting with disassembling an Exa II down to the mirror box and shutter and reassembling it successfully,
when I was 14. I've cleaned leaf shutters and done minor repairs, cleaned and adjusted (and modified) the frame counter in my Super Ikonta B, repaired damaged focus threads and reset the focus sync on my Kodak Reflex II -- that is, I have a fair chance of repairing at least some things that might go wrong with a mechanical camera, and I'm pretty good a troubleshooting mechanics (I repair mechanical, pneumatic, and electrical -- but not
electronic, we replace electronics as modules only -- items for a living).
I have no such skill or history with electronics. I don't "get" them.
Therefore, I'm much more comfortable with mechanical cameras than with ones that depend on electronics for the most basic operation. Metering is fine, I have three working M42 bodies with TTL (stop-down) metering, and have no objection to a camera that has a built-in meter -- as long as I'm free to ignore it and the camera will continue to work if the meter electronics fail or the battery is removed. In the end, I don't much care how "reliable" late-generation electronics are. The electronics in cars are pretty reliable, too, but take a look at the number of electronic-related recalls any given year.
I get more and more impression that the Arax 645 isn't the right thing, either -- as noted, it's a 6x6 SLR with a mask and adjusted film advance; it's bigger and heavier than a 645 needs to be. But apparently, no one ever thought to make a 645 SLR until after you couldn't sell a professional camera without it depending on batteries and electronics.