I've tried most of all of them out there (FC660C, 30g - 55g Realforces, Typeheaven) since I've been able to access them in stores. I settled on the HHKB because I prefer compact boards and the HHKB layout was really intriguing (and definitely worth it so far ). I'm interested how others would feel after an extended period of time though, I've been eying Realforces
I understand that, and I currently own the Leopold fc660c and the Realforce 87u 55g. I will be honest I absolutely love the HHKB and it's layout. My friend and I were talking about the perfect compact board would have the Leo's alpha keys, HHKB's modifiers, the layout for the HHKB, the feet and metal plate in the Leo, but the weighting options of the Realforce...god with pbt caps. LOL, anyways I am currently in search of a purple and or grey escape key for the Realforce 87u which has been the main board since receiving it a few weeks ago. I will not say I like it more than the Leo, but the typing experience(after letting it break in and you grow use to it) is quite literally the best I have had as far as anything over 45g. I love the Leo as well for it is both well constructed with that nice bump before the smoothest transition down to the back plate.
I did not have the money to buy some HHKB key caps to put the alpha caps on my Leo, because I was building 2 computers(one for mother, the other for my girl's new gaming rig) and then I found a Fractal Define R4 for sale and had to grab it. Now, that it is all done other that some minor things I will be getting those caps soon.