I have some Koalas and T1s in a switch tester, and I can't tell them apart aside from the spring weight. Out of the box they're both pretty rattly sounding with very sharp tactility, but after some 3404 and switch films they're extremely smooth and feel like a super tactile Topre switch.
Zelios V2s are much better stock than Koalas/T1s but feel equally smooth after lube. The 3 actually feel very similar when typing quickly, but when you push the keys slowly you can feel that the peak of the Z2's bump is a little lower and that the bump extends pretty much the whole travel. It also means they have less upstroke clack, which is pretty bad on unlubed T1s.
Take this with a grain of salt btw, I have a whole board of Koalas but my Zeals and T1s are just on a tester.
