In all honesty, both of my m-tronic machines have been flawless. Absolutely flawless. Mike, if you get in the FHC secret Santa gig next year, pray I get your name. I'm so sending you a box of those little orange screwdrivers. I have dozens of them! Funny story: I was at the dealer picking up parts and I made a comment on how much I love the little orange screwdrivers, as they are a great size and can easily be modified into all kinds of "custom" tooling. My buddy there picked up 4 or 5 fistfuls of the things and threw them in my bag.
I've never seen/heard of a 291M.... It's not just the mtronic stuff creeping up prices, it's a combination of more sophisticated AV systems, stratocharging which introduces another set of ports and a more complex piston to machine plus dual throttle butterflies on some units.