Sorry to bring up such an old post but I wanted to bring a a less expensive alternative to all 7cap radio users. its called programming,
if you set up a user program and hook up the the second elevator channel to channel 7, you can use channel 7 as a slave to channel 2 which will be the master elevator channel. Set this program as null (meaning always on) set up your epa and sub trim channel 7 for parallel operation with channel 2 and it will work the same as any other mix on any other computer radio. I guess futaba just plain forgot to explain this in the manual (pretty stupid on there part) but the radio does have the ability for dual elevator servos.

I also have a 7cap, and I am looking at black horse bravo 303 pattern plane which uses dual elevator servos and I was very upset that I would need a synchronizer for the second servo so I while reading my instuctions I found out why futaba added 3 user defined mixes. I still think they should have added this as a setup procedure in the book.

Rc-plane as long as you set the program to 100% synch with channel 2 you should have no problem with trim I am in the process
of setting up this program on the bench with servos and I will post the setup instructions once I have it all ironed out.

Well guys I am a moron for more reasond than 1 first off the trim doesn't work for the slave servo, 2nd for the money paid for the 7c
and the fact I have to buy a synchronizer I could have easily got a 9c. Well we live and learn.