FINALLY, I can get this out there...
I have been using an internal MidiJet Pro inside my ZX since 2005. I had asked David about it back in the day, but that was long before ZD was able to distribute the MidiJets OEM, so he couldn't offer it. So I decided to take matters into my own hands... (yes, voiding my warranty. Fortunately Zendrums happen to be indestructible
I soldered some short cables inside my ZX (one for power, one for midi) and removed the circuitry from the MJ transmitter. I placed the stuff in the ZX body cavity, and hooked 'er up. If you have checked, the MJ uses a 9v AC adaptor. Sound familiar? Same voltage as the ZX. David added a 9v battery box to my ZX, and I was good to go. I have been doing this for over 4 years and have never had any kind of trouble with it. I get 5-6 hours out of a single Duracell 9v, which is running the ZX AND the MJ. It's really slick to have NO cables hangin' anywhere!
So, having road tested this exact gear for 4 years (with NON-professional soldering, mind you) and no failures to date, I am tellin' all you guys: GET IT. It will simplify your world and make dancing with hot chicks while playing WAY more fun (if that's possible???