I just got one late last week. Nice engine from a material, casting and machining standpoint, but I'm just not a fan of all the angled cooling fins. Engine should be designed to run well, don't have to "look good." It's almost a full 2 ounces heavier than a ST.51. The EVO .60 weighs in at 12.75 ounces on my scale, and the ST.51 weighs in at 10.9. The crank case is bigger, which translates to bigger, heavier bearings, and all the extra aluminum from the cooling fins. The cylinder is much thicker and deeper. I haven't compared it to the venerable ST.60 yet but will do that ASAP. It won't drop in where a ST.51 mounts, so I don't know how long it will be until I get a chance to fly it. No instructions on break in, but warnings about not licking the engine or putting it in your mouth! It will be a good deal for the money if it makes good reliable power. All the extra goodies that come with it won't be much consolation if it doesn't perform well. It's good to see a dedicated stunt engine on the main stream,general hobby market, though. Maybe more will follow.
  Type at you later,
  Dan McEntee