sounds like you already made up your mind. so just get the airtronics.
i came from futaba to airtronics, mainly cost driven as i didnt want a 4pl but im very very happy with my mt-4. i would probably get an m12 down the road, depends how many rx's i have by then.
airtronics rx's cost more than futaba rx's which is a consideration. but you can use any fh2-3-4 rx with it so if you dont wanna spend $140 on a 471, you can get a 744 or similar rx for say.. $89. less used.
futaba your limited to 603/604/614 models though they are cheaper.
futaba is 100% reliable. never ever ever had a runaway with it or loss of signal or any interferance period. my airtronics has been reliable SO FAR, though i had the odd wobble from interferance which hopefully was isolated to borrowing someone elses rx. of course, fh3/4 is faster on paper. in vrc my average laps became more consistant and fastest laps went up but that might also be a comfort thing. very comfortable, lightweight radio.
its also worth noting that the new menusystem for my mt4 and probably similar in the m12 is SO MUCH NICER than futaba's card catalog style of menus.
with chset menu you can change every option available for a channel in one place isntead of having to flip through all the different ones to do it.
the telemetry really doesnt work that well lol. rpm sensor isnt reliable, temp sensor seems ok. but thats a nitro car.
sorry for long post, just my impressions. mt4 is my first airtronics, 3pks was my second futaba. both futabas were excellent, and for the money spent on my airtronics, its above excellent. id have to find someone with an m12 and see if they'd let me do a race with it to feel if its worth $300 more.. but im still using it out of the box ha. set epa and brake atl, and nothing else.