I must have had 20 or so Evolutions on students planes so far. Mostly the .45TPS, but a fair number of the 60 size as well.

I've never had one that didn't run well.

I've had several where the factory set low speed limiter was off so that the low end couldn't be leaned out enough. Takes a few seconds to remove the limter and lean out the low end.

I have a used and abused Evo .45TPS engine on my LT-40 that I bought cheap after an ex-student piled in his trainer and moved to larger planes. I pulled the baffle on that one, and you get considerably more than 100rpm with that mod. I also turn an 11x5 prop, and it will haul my LT-40 almost straight up. With the baffle out, the power is close to the OS .46AX. It does make more noise than with the baffle in, but less noise than most other engines in it's class, that Evo muffler is really quiet. My OS .46AXes with Slimline pits mufflers are much louder than the Evo with the removed baffle.

On the Evo carbs, the low end does affect the high end mixture and vice-versa more than on the OS carbs. This isn't a problem, and it's common on a lot of engines. But if you approach tuning the engine as if the two mixture settings are totally seperate you can get real frustrated.

Lots of people have favorate engines. It's funny reading someone bad-mounthing an engine then swearing that their favorate brand is the best. Look around, and you can find plenty of people who have had problems with that same person's favorate and have sworn off that brand.

IMnsHO, OS makes great carbs, but they use nickle plated liners that wear out faster than the chrome used in many other makes. And the whole plastic backplate and plastic needle valve assembly thing is for the birds. I've seen dozens of plastic needle valves get the fuel nipple sheared off. On a conventional needle, an easy out would pull the nipple, and a new nipple is a few cents. On an OS, you have to replace the whole needle body. And then there was the whole OS .46 liner pealing problem a while back. Seems like they have it fixed though. That said, I own several OS engines, like them, and use them. But they aren't perfect.