The buckling spring boards with lighter actuation force are:
- IBM Model F variants. Not so much lighter compared to Cherry MX Blue.
- Boards made with ALPS buckling spring switches. Supposedly as light as Cherry MX Blue but the better buckling spring feel. Very rare.
The
IBM model M2 has the same springs as the
model M, but it has a much flimsier flatter construction. The keyboard is not curved and the key caps are shorter. It is louder and the feel is not as "solid" as the
model M.
Be careful that many
M2s have broken electronics, even unused pristine specimens that have never been outside the original box. The problem is that the capacitors dry out when they are not in use. Be also aware that there are also rubber dome variants of both the
model M and the
M2.
There are two kinds of "space savers": The vintage "Space Saving" version of the
model M that had away with the numeric keypad, and the
Unicomp SpaceSaver. Unicomp sells a version with a trackpoint called the
EnduraPro.
The vintage one is the one that costs the most money ... especially the unusual "Industrial" version with darker grey case.