RE: 40MHz or 2.4GHz?
if you only have 1 boat then go with the spektrum dx5, dx3r or even the likes of futaba and jr do 2.4gig systems
i love spektrum because if have the dx3s (like darla, how are ya girl?) and with the sr3300t in my boat i can keep an eye temps, rpm's etc, they do the sensors for electric and nitro