That tiny ass spacebar sucks. The enter key is huge and ISO style. The tiny gaps on the bottom row is awful design.
If that wasn't bad enough, the backspace key is only 1u, and difficult to reach as it's positioned way too far away.
The whole point of having a tiny spacebar for a non-japanese person is to be able to very easily reach modifiers left and right of the space bars with the thumbs. As a result I'm using Alt, AltGr, Ctrl, Shift and an additional "Super" modifier (so that's five modifier instead of typically three... Sometimes I'm considering adding an "Hyper" modifier too). I touch type but I "incorrectly" only ever hit the space bar with my right thumb (instead of alternating as the touch-typing gods meant it to be if I am not mistaken), so that allows me to constantly have my left thumb on the modifier at the left of the tiny space bar: this is great because I don't need to distort my thumb, it just feels natural.
Who's reaching for backspace? That's modifier+'h' for me to delete a character backward and modifier+'m' to do "enter".
Tiny gaps? I hardly ever use the function keys and who reaches for the arrows? There's modifier+{i,j,k,l} to simulate the arrows. So I didn't even notice that gap until I read your message...
I'm not just after a good switch: I'm also after having the most efficient setup possible. For example one modifier is dedicated to all the shortcuts related to the window manager (switching virtual desktops, resizing windows, closing windows, etc.): that's very convenient (and fast). My keyboard's layout ain't perfect? I'm not forced to use every single key...
I've been typing on IBM Model M for years and have tried many MX switches and I even have a white ALPS board which is kinda great to type on... Yet after reading about the particular feeling of Topre and how they were so great, I decided I had to try an HHKB to see what gives: best switch ever IMHO. Maybe not for gaming: but I don't play games with my HHKB.
Now I'm not saying the HHKB Pro JP's layout is perfect and I'm not saying I wouldn't love a real ergonomic keyboard with Topre switches: say an ErgoDox or a keyboardio/butterfly design but with Topre switches. Actually I'd love that: I'd fork out $500 in a heartbeat to have such a beast (and, no, I don't like the µTron's layout at all)... But meanwhile I'm a happy camper with my Pro JP