Disclaimer: I have never used and Evolution engine, so take my opinion with a grain of salt.....

OK... there are a few people who use them at our field....
One is a good friend of mine... he had the .46 worked great on the test stand.... but never reliable in the air..and he (and the several other people who have helped) knows how to tune engines...
He is now borrowing my OS .46ax so he can fly...
The wierd thing is it ran fine last summer

another gentleman has an Evo .46 in a trainer..... if the temp is remotely cool... the engine will not run...and MANY people have tried tuning this engine...

Now, I'm not saying they are bad... and these may be very isolated instances related to cold weather flying....
but I don't think I would be in a hurry to grab one....

Just my very humble opinion