I moved from the Keytronic KT800 to a Filco MJ2 and felt the same thing. The keys felt smaller, even though visually they looked identically in size. I bought a Novatouch shortly after and felt the same thing.
I am actually wondering if this is to do with the fact that on the Keytronic keyboards, the keys sit a little higher above the case of the keyboard itself (you can see under them), whereas on the Filco/Novatouch the keys are somewhat sunken into the case.
Makes me want to find a mech keyboard that has keys the same height out of the case as the Keytronics just to see if this is the reason.