Yeah I think it is just too ineffective and unstable... But it´s a cool idea, definitely.
How about have a Tricopter that can hover normally like all the others do but if it wants to go for normal flight it tilts all 3 motors to the front ( or switches the rear one off and the front ones pull the "plane" only) sothat you have a normal plane then.
So basically VTOL!
I know, the conversion between the two sets will be difficult to program. I thought of probably getting a wing, so that it starts to glide for a while until the motors switch to the front fully and then you can apply some throttle again for quicker forward flight.
I think I have seen a video a little like that on youtube. I´ll look for it.