I've a bit of experience in using iOS devices as alternative input controls and would say BlueTooth is too buggy.

In the past I have used TouchOSC and the OSC protocol over Wi-Fi (which I believe is 2.4ghz) which should be more stable.

Points for innovation though! I dunno who did the Wii Contoller / Board work for the Gadget Show when James and Grant made Satan's Mutt but they interfaced the Bluetooth controllers with a 2.4Ghz standard controller and used that to transmit.
I know 'Running in the Halls' did all the coding work for the BF3 simulator so could be them?