Well, your first line has already taken care of my usual response regarding aftermarket bezels! (i.e. don't do it, the setting is never as clean as OEM, you can still see the ends of the minute markers on the bezel, etc, etc!)
So as you've already made up your mind to get one, all I will say is that the biggest issue you have buying aftermarket diamond bezels is making sure that the diamonds really are the colour and clarity that they are advertised as. It's this that seems to cause the vast majority of negative reviews that some online sellers get. Personally I'd steer clear of SI diamonds as it usually IS possible to see the inclusions with the naked eye, but I guess it depends what you are after and what your level of acceptance is. I don't mean this in a derogatory way at all, so please don't take offence, but if you're already happy to buy an aftermarket bezel that will show overcutting at the edges where the bezel is cut to fit the diamonds, and you're happy with still being able to see the ends of the minute marks on the bezel, etc, etc, then maybe the inclusions in the diamonds won't bother you either - it really depends on how much of a perfectionist you are. I've always been an absolute perfectionist, so if I was into diamonds on gents watches (which I'm not) then I'd have to go the OEM route. (I guess it's lucky I'm NOT into them or else it'd cost me a fortune!)
The bezel on the link you provided looks OK (subject to my comments above), and I've certainly seen worse aftermarket bezels out there. However there's no way to really tell what the diamonds are really like until you have them in your hand : you just can't tell all that much from pictures. That said, the seller's reviews all look very good, so as with the bezel itself, I've definitely seen worse sellers out there too.