I followed the link about the Onyx allegedly overheating and found this:
"So I've opted to not return the 2 onyx that had some sort of glitch that made the thermal shutoff circuit shut them off within moments of powering up.
Mike at Rapid has advised me we can still trade them out with two new ones.
The thing is they haven't turned themselves off again that I know of." - dbkick, Apr 17, 2014
"every one of my Onyx are operating just great. I dunno wtf that first glitch was , it may have been my fault and I bumped some wires like I said . But it was very strange and had me worried (although they were and are still covered by warranty and Rapid does stand by their product). I probably shouldn't have said a word about it since I THINK I could have been at fault." - dbkick, Jun 4, 2014
Even still, I am having a hard time choosing between the XGS-190, RW-150, and the Onyx Bloom.