I'd be pretty leery of any Chinese engine EXCEPT ChangFa from the stories I've read.
I've got a Powersolutions/Changfa R185 and I'm just absolutely pleased with it. It runs like a Chinese copy of a Swiss watch.
I have about 6 hours on it so far, and did the first oil change this weekend. The oil came out just a bit black, of course, but there was almost nothing in the way of grit, metal, sand, chunks, etc. Just a few little particles here and there. I was really expecting a lot more garbage.
It also runs very smooth, the only real vibration coming from the actual power pulses.
Chris