Just a precision about the DPSI twin it does not request a seperate band if using two freq's, well in fact it depends which twin HF module you would be using. If you would choose the Emcotec twin HF module then yes you would need to plug two different band rx's. If you would choose the ACT twin HF module then you could plug to rx's in the same band. This is specified by the TX not the RX. As said before I don't think any of the 2 systems use proprietary RX's so you could use ACT twin HF module to run DPSI-TWIN. For the 8 channel limitation I wonder about if this is an issue in case of interference that you would be unable to lower your tailhook ? Seriously as long as you have all vital controls plug on those 8 channels and the remaining channels on either rx directly I don't see it as a BIG shortcoming but again this is a fact and I don't discuss it.

Regards
Sk