RE: Buddy Box question
I buddy box with my Daughter with a DX6i and a DX5e. The Expo does not carry over and I have not been able to find a way to make this happen unless I use another DX6i with a Model programmed with the exact same Expo and trim settings as the Master. It's a real PITA and we generally blow this off as I use the Trainer when she's flying.
As I understand it, there is a programming "Ping" mode you can use with the DX7 to allow the Slave unit to mimic the settings of the Master, DX7. I'd get ahold of Spektrum and go over this if it were me before attempting it.