In my experience I've not encountered such problems with 2.4 radios. I do keep some separation ( a couple inches or so), and keep my wiring segregated, but mostly for serviceability. As well, my observation has been that you don't see many guys flying helis at 72mhz.. look at how close the gear is crammed into those canopies. To conclude, I wouldn't say mount everything on top of each other, but wouldn't lose sleep over some components being a bit close together either.