Respectfully, I totally disagree 100% with the NEED to stick to 4-6 channels.
What I do agree with is that a beginner needs to leave the advanced functions alone until he/she actually understands what they are used for. IF the person is mature enough to just stick with the basic functions, whether it has 4-6-9 or 20 channels and 100 mixes wont make any difference. Im not their father trying to protect them from the big bad world, Im trying to help them make a quality decision that they wont regret.

Now I have sortof reversed my philosophy on what to start out with... If a beginner WANTS to startout on a comp rado, then by all means get at least a GOOD 7-9 channel radio, they arent all that much more expensive. ALso the cost differential between 7 and 9 channels isnt that different, thats why I say go to the 9 because if you have the money, and you really are going to fly planes with dual servo or multiple servos on one surface you will NEED the channels. If you cant afford anything but a 6EXA then just get a standard 4 channel radio for $125 and when you are ready to commit, upgrade to something that will last you forever. The minimum would be a JR8103 or the Futaba 9C. Funny thing is, both are just as functioal and maybe more user friendly than the 9Z, 10X, 12/14Z models they just dont have the bells and whistles.. They are an INCREDIBLE value for the money.

7 channels is the bare minimum if you are really going to be serious one day about this... You can get away with less, but one day you are going to be setting up a plane and you are really REALLY going to wish you had those 7,8,9 channels I promise. I know because I setup "more advanced" airplanes all of the time. You just cant do it RIGHT on 6 channels.

Look, I actually fly more advanced airplanes in a competitve atmosphere so Im not just blowing smoke here. From a purely practical standpoint you are not going to want to fly a "more advanced plane" on a $200 radio especially one that limits you to 4-6 channels, that is a 100% guarantee. 4-6 channels just arent enough when you start using dual servo setups. ANd if you think Y harness will cut it, think again. They are ok in some instances, but if you want to fly with any precision, I mean real precision you can forget it. Channel 5, on most low end radios even on the 9C sortof limits what you can do on most transmitters, so unless you are using smoke or retracts its sortof a useless channel

Here it is all spelled out, you can somewhat mix match channels but heres a general application.
Channels
1- Left aileron
2- left elevator
3-throttle
4 rudder
5- smoke/retracts
6-right aileron
7- right elevator
8-2nd battery pack (if you want to use it. )