RE: FHSS1, 2, 3 4, 5 ,6?????
There's almost no cost difference between a 4 channel and a 6 channel radio in terms of the channels themselves. So, when you guy a 6 channel radio you're not really paying much more for the channels, you're paying more for the functions. Mixing, Expo, EPA, Multi-model memory.
So, for example.
Aero-Sport 5 with Airtronics FHSS1 technology. 5 channels, No Dual rates, no EPA. Radio has servo reversing, v-Tail mixing and delta/elevon mixing. consumer price 60 dollars or so.
Airtronics SD-5G with Airtronics FHSS1 technology. 5 channels, 3 model memory, fixed 70/100 dual rate, motor cut, trainer compatible, ATV on flight controls and EPA on throttle. Digital trims. Price to consumer, about 110 dollars.
Airtronics SD-6G with FHSS1 Technology. High functioning mixing, Expo, Epa's, programmable mixes, helicopter functions, multiple wing types, dual elevator servo mixing, trainer compatible, adjustable dual rates, etc. Consumer price about 170 dollars.
So, you what you paid more for are the very functions you requested. The added channels were not much money.