The $170 price tag isn't outrageous, IMO. It's a great radio and comes w/ the dang near top of the line rx. The good thing is that you can use the FHss-2 rx's which are cheaper, around $50 or so new.
The spektrum stuff has a cheaper feel to it, IMO. Plus all the problems w/ brown-outs are not cool. I know that there are fixes for that stuff, but you'll still have extra stuff on the truck that's not needed in other cases.
The dx3r is $250 w/o a rx. $339 w/ a rx.
Spektrum has cheaper radios than the MX3X, but they're not a nice as the airtronics. IMO.
The dx3c doesn't look to bad, it's priced right and if your willing to deal w/ the weak bec/ strong servo/ spektrum rx problems that come up it's ok.
There's a ton of Spektrum radios around the tracks I go to. So they must be ok. ALthough, none of the "pros", are running them.
I'd recommend the MX3X to anyone racing.