I currently have an M11 with a 2.4ghz Spektrum module.

I'm debating getting an M12 or an MT4.... would the MT4 be a good upgrade from the 2.4ghz M11? Is the M12 worth the extra $350 over the MT4?

The MT4 is super easy to use..very light weight but no backlight.
The mt4 is not a budget radio it has just about everything all the heavy hitters have, the best value period.

The m12 is quite a bit heavier but has a ton of options.
Dropdown, angle adjustments, two wheel sizes, etc..etc.

I have had the mt4, m11x and now the 12.

At the of the day it will depend what you will using the radio for.
If you're only using it for one single thing..then see if the MT4 has what you need.

would the m12 dropdown work on the mt-4? looks like the same wheel assembly.

I have an MT4 and it feels like a high quality radio. It has everything I need for racing. I still have not used all the features to my advantage...

Keep in mind with Airtronics - the receivers are pricey.

No more so thab futaba i noticed. Going rate for a 92451 used seems around $70. Think my futaba 603fs's were $65 used.

Sure its not spectrum but not that bad.

I think someone posted that they asked airtronics if the drop down would work for the mt4, and they said no.

I would say go for the mt-4 has all the features you will and will not use, not to mention telemetry if you like that sort of thing. Kind of like how futaba has the 4pl and then the 4pk. One has all the feaures you need and then some (4pl) and the other is a fully loaded radio with features you'll never use for double the price

But if I could afford it, Id drive a Ferrari EVERYDAY

im in the same boat you are, and i just ordered an mt-4 last night.

the reality hit me when i dropped some tenths using my friends dx2s over my 3pks. my laps were more consistant and i actually used my brakes accurately for the first time ever.

pretty sure my 3pks was a higher end radio but the spectrum was more comfortable.
i might miss the dropdown, but all i ever used on my 3pk was expo and fs. to further salt the wound, i did the same laps with his xp3-ss system. so really. all the features and speed are nice, it takes one more element out of the mix, but in the end, all about the driver.
buy the radio you LIKE best.
now i can spend the extra $300 on replacing 4 receivers. and hey, once you get into an mt-4, your not starting from scratch if you DO want an m12.