I have had Roos with a RAM 500, a PST 600 and a RAM 1000. The ones with the smaller engines are a delight to fly. Vertical was good, but not unlimited. They topped out around 140 to 150. The vertical on the one with the RAM 1000 was to say the least.....awesome. You can't go wrong with a composite ROO and a 12 to 14 pound motor.