As you can see in the video, it will do some good 3-D stuff with the Saito 100. It will probably perform as well with the 91 Surpass, but for hovering it would be marginal at best with either engine

An OS 120 or Saito 125 would be better choices, Or a YS 110 (which would allow you to move the tank back to the CG if you so desired.

As far as 2-strokes go, my conscience will not allow me to recommend one.

PS, here's an interesting piece of trivia... After that video was shot, I removed the canopy to discover that I never installed the Rx antenna. It was just laying in the bottom of the radio compartment like a rat's nest. [X(]