They essentially feel like rubber domes.
If you were to remove the rubber "sleeves" and replace them with springs, I could imagine you could make these into short-throw linear switches. Something I have always wanted to try, but I just don't know where I could obtain the appropriate springs.
The M4-1 was the first keyboard I bought after joining GeekHack. Overall, it's not a bad keyboard. I used mine for a good long time before I got a Model M.