The 3 mixes are any combination of the from the list below the words 3 mixes. What you are looking for is a radio that will allow you to program another unused channel to follow your elevator channel. The mixes that are listed on Futaba's web site are some what typical for most radio's. Here is the specs for the 9C. It has 7 mixes available and elevator mixing is one of them.

http://www.gpmd.com/cgi-bin/wgpinf100p?&I=FUTK9200

Don't get me wrong, the 7C is a great radio and I just love mine. I was not thinking about elevator mixing when I got mine and now that I have planes that need elevator mixing, I am using my older radios that have that feature. I just want you to purchase a radio that is going to do what you want it to do and have the features that you need. I personally believe that if you can eliminate a match box, a reversing Y harness, or a Y harness you are flying with less to go wrong. Good Luck, Dave