I have the Twinstick, and it is great flying model. Mine is flying on 2 Mag .40XL's. It will climb faster than any stick I have ever flown at full throttle, but slows down nice for landings. It is also easy to handle on one engine with zero offset, on either engine. I have lost an engine several time with no bad habits.
I understand that the newer kits are good bit better quality than the earlier ones. Mine had a lot faulty glue joints, however Niel told me they cured the problem.
Like Ed, I put the rudder and elevator servo in the rear to help with balance.