Pierre1976,
I am a fellow Raven One owner (a variant of it, A raven 2). The 3 unit motor will actually work on the Raven One (I am planning on ordering one shortly!). Email Jeff for more details (his line has been down since he has been hit by Sandy pretty bad). His email can be found on his website.
Additionally, I have been experimenting with the raven MC units. If you have not already tried, you should definitely experiment with the AC or even the BN MC. I have tried both and am pleasantly surprised of how great and simple an upgrade it is.
-Assad