1. I have read that blue alps are "smoother" than white alps; based on my brief test, it's difficult to tell whether they are smoother or lighter, but it's definitely one of the two (or possibly both), although only slightly so.
Yep, both smoother and lighter. The difference is relatively subtle though.
3. The Matias switches have an inconsistent click based on where you hit the key - striking the key dead center produces the normal click, but striking it off to the side produces a softer click or even no click in some cases; in contrast, the white and blue alps produce a uniform click across keys and with no dependence on where you strike the key
In my experience, all clicky/tactile Alps switches have a slight inconsistency in click w/r/t press angle, which is detectable if you lean in close and listen/feel very carefully. It’s definitely much more pronounced on simplified Alps switches and various Alps clones, including Matias switches, than on “complicated” Alps switches. Complicated Alps switches have a substantial metal leaf on either side of the slider, which stabilize it laterally, redirecting angled presses downward a bit. They also have tighter tolerances between the slider and housing.
4. Interestingly I think my Cherry MX blues have a slightly louder click than any of the ALPS boards I tested, although I prefer the lower pitched ALPS click
Loudness is hard to rank, because the sounds are quite different, and different vibration frequencies propagate more effectively through the case/table/&c. The material and design of the case makes a dramatic difference in the sound, as does the material used for the keycaps, the plate and PCB, etc.
A loose cherry MX blue switch with no keycap, outside the context of a keyboard, makes hardly any sound at all. Add a medium-thick ABS keycap, and mount it to the right PCB, in a hollowish plastic case placed directly on the right wooden desk, and the sound will carry across the neighborhood.
