How many channels is enough?
And if you look at the suggestion that Lynx mentioned, you would still have your 8. However, 4 of them would be mixed and setup on the receiver, and thus would not need to actually use a channel transmitted from the transmitter.
For example, you need two channels for each servo on the elevator. However, all you need to transmit from the transmitter to the receiver, is to either move the elevator up or down which only takes 1 channel to do this. The other channel used is pretty much a duplicate of the primary elevator channel save the end points and sub trim. The receiver would then take that command, and split it into two channels out to the servos. You get the benefit of two channels in the airplane, but only need one channel link between the transmitter and receiver.
We currently do this with the matchboxes, where we take one channel, and turn it into 4. All the ATV's, and sub trims are set in the matchbox, and not on the transmitter. If the manufacturers incorporated the functions of a matchbox into the receivers, we could easily get more channels, or higher refresh rates on the primary channels, etc. Lynx brought up a good point, but for a different reason being refresh.
I would leave our current refresh alone, and just allow more channels at the receivers end. Viola, we now have 12, 14, 16 or more channels at our disposal.
We can actually do this now with 4 matchboxes if we desired. But, if they made a smart receiver, where you have the standard 10 channels, but also had an additional 6 channels locally mixed to a primary master channel (ail, elev, rud, th), and have it configured at the transmitter and downloaded to the receiver, that would alleviate us from having to use transmitted channels, which are basically duplicates of the primary channel.
Hmmm..interesting thoughts Lynx...