Hey, I also fly at Georgetown, where Brett used to practice. I've never seen the wings shake while taxing since Brett always carries the Euphoria to the runway and later kills the engine instead of taxing back.

I confess that I use a YS170 DZ with CDI. From time to time I have some problems but I like the engine anyway. In response to Plakman, I use a Thunder Power 1900 Ma Li-po, 7.4V with a Digi-switch with regulation to 5.7V. With this set up I normally make 3-10' flights and recharge it. It always shows about 700-800 Ma of capacity used.
If you get a used engine, it'll be easier to find a 170, but if you buy new go for the 175 since this engine has a few improvements over the 170.
Good luck with any choice.
Rene