I have the Evolution's... and they are powerful, but I have seen two come apart in the air... Horizon fixed them... but I'm a little nervous with mine.. The pilot was running 40:1 oil mix, spinning a Menz 22x8.... The ring broke on both occasions, without any warning... The engine was actually a tad rich on both needles....

They are a little pricey IMO.... You can buy a 3W80xi for the same amount, and put that in a 18lb bird.... watch the weight of the other stuff, and that would be a ballastic machine.