There's a big caveat, though: not all Model M keyboards were the same, so the comparison might or might not ring true depending on what Model M you used. For example, the one that came with my PS/2 Model 50z back in the day was heavier and sturdier than some of the ones that IBM made later, and had a removable cable. The Unicomp stuff compares to what IBM was making immediately before they gave up on the whole business, I think. Then Unicomp eventually made some USB keyboards, which turned out not to be the greatest...
And yeah, the Model F was a completely different thing entirely.
(edit: in truth, I haven't bought anything there in a little over nine years, wow... their Classic 101 still looks pretty legit)