Got the concrete set. It looks great and feels nice. It's disappointing that the frame for my G. Skill keyboard barely accommodates these keys since they're slightly larger than the stock keycaps. Some keys (right arrow, Pause, Esc, etc.) get stuck. To alleviate the situation, I throw in dampeners (as much as 2 o-rings) so they're sitting a bit higher. Other than that, I'm happy with this purchase.
blakstealthYou'd probably get a much better keycap seating and feel by just filing the corner down slightly until it's no longer making contact. That's what I did for a set of keycap that we're grabbing like that in an RC930. If you're careful with it, it won't be noticeable.