The motors only really need to be sent back to Tac if you blow a winding or if you arent comfortable doing brush changes on your own. As far as maintenance goes, just keep your barrel clean and occasionally take apart your cylinders to clean and lube the seals in there.
Another option that you could consider since you're in the states is the APTW made by Z-shot. They're incredibly high quality, as they should be, and I think their bodies are all milled out real firearm receivers. Same quality internals as well and the motors are supposedly very good as well and should last a long time.
Lastly to address your concerns about the bolt catch function, I would suggest looking into the HAO magnetic bolt catch. It uses magnets instead of a spring so its far more reliable than the original spring actuated bolt catch. I have one in my PTW and the rest of the guys I play with also use this bolt catch or the original (but discontinued) systema magnetic catch.