Which ARF Bipe?
I have the DP 1.20 size ultimate and it's one of the best flying aerobatic planes I've ever flown. It really makes a good pilot look great and a great pilot look like he's on his way to the TOC.
There service takes a bit to get used to, but on the positive side there are not a great deal of them out there. You may be like me and be the only one at the field with one. Kind of cool in a ARF world.
I also had a Goldberg which I built from a kit and although this was a great flying airplane, I believe the DP is better.
Real fun to fly. Oh go with a four stroke just for the sound.
Mike