Have it in one of mine (104" PBN Nomad) and there's no range problems. Why would you think there would be range problems in a float plane that aren't there for a wheeled plane? Range is range, no matter if over water or ground. I especially like the idea of the DX-7 for my float planes since I fly mine off my pier and there's a couple of other guys that also fly off the same lake. By having the DX-7 system I don't need to worry about one of them being on my frequency, even though the distances between us are such that it's unlikey that there would be interference problems.