Well, I just got the HHKb in the mail today, and my god, cupped rubber really is something else. This is an incredibly strange feeling that I'm having right now. I don't know how to feel about cupped rubber, or MX anymore... I like it so far, the smoothness is incredible, and I really like the sounds, ugh!!! Getting used to this new layout is going to take a bit, but I'm liking it so far.
Also, it's very stealthy, being that my MX board is bright blue with white keycaps, and this one is black with printed caps.
I bought this board with the intention of selling this, or the MX board, and my decision is now very difficult, indeed.