I have not tested the Sun Type 7 but I would bet that it is the same Fujitsu rubber domes as in Sun Type 5 and Sun Type 6, and in other Fujitsu keyboards I have tested. They are very mushy.
AFAIK, the Sun Type 6 and 7 talk USB. The Sun Type 5 is better quality but talks only Sun's old proprietary protocol.
Except for language variants, all of Sun Type 5c, 6 and 7 have the same layout. Some Type 5 have a more Unix-like layout with Ctrl next to A (where it should be!) and Backspace a row down where the \ key is on these boards.
By the way, some of these keyboards came also in tenkeyless versions: No numpad, but still a function cluster on the left hand side.