As far as I can tell, and I am not an expert, the HHKB line up goes something like this:
1995 Happy Hacking Keyboard
1999 Happy Hacking Keyboard 2 + Happy Hacking Keyboard Lite
2003 Happy Hacking Keyboard Pro + Happy Hacking Keyboard Lite 2 (USB 1.1)
2007 Happy Hacking Keyboard Pro 2 (USB 2.0 and Rohs)
Only the pro's have capacitive switches, all the others are rubber dome.