I just put the three blade head from flying-hobby.com on my #2 TRex in preparation for making it a scaler. This head is quite a bit less expensive ($100 complete) than the Deetee version, though theirs is nice in that it uses some Align parts.
You can fly a multi-blade head without a mixer or gyros, you just have to be aware that the flight characteristics are different. There really is no performance gain to be had. If 3D is what you're after, stick with a flybar head...
TRex 600E/ JetRanger
TRex 600E/ AStar
"The welfare of humanity is always the alibi of tyrants." - Albert Camus