Dark Wombat,

Its easier to roll it upside down then flip it.

Build up some airspeed, then pull the nose up, and roll it over. Kinda like a barrel roll, only you stop it inverted.
You can also fly it backwards building up some airspeed, and then flip it forward. It does need more power though for good 3D aerobatics. Ive got mine as tweaked as I can get it, and I could still use more power.