Yes, all of the Devy parts (except the forearms) released-to-date are compatible with a genuine Hasbro/TT Devastator, as well as the high-quality Chinese KO. Among the recent KO reissues, Devastator is one of the better ones. The Chinese KO costs about the same as a decent 'used' orginal, though. The difference being the 'freshness' and the box/styrofoam included.
Plastic is a little softer in some areas, also.
Note that you'll spend more on the Devy parts than you would on all but mint/unused G1 Devastators