G660 is a China ver of ms660. From what i just read it is not a professional saw. But with 92cc maybe it can mill me enough boards to build my shed. Or may be not....I have no idea how the g66 is but I would think a 660 would do fine. We used them in the last old growth unit I cut on, can’t remember what year but it was up in the Tacoma watershed, and no issues. There was a lot of 6 and 7’ trees which is kind of a similar type workout on the motors. Not sure why the inside clutch has issues on my 385 but the shoes are very different so maybe the stihls don’t have the problem