Stoneke:
I fly at 3700 ft or so, using a G-38 with a 17 x 10 Zinger prop. The plane weighs about 18.5 lbs. Powerwise, its OK (kind of scale), but not extra fast or unlimited vertical.I have no experience with either radial, so based on looking at the prop size and some quick prop calcs, the 170 performance (speed and thrust) look similar to the G-38. The 200 with a little more speed and thrust would be nice.
Brian