I've not found Gatorskins particularly hard, but I've only put them on Mavic rims - old MA2s, Open Pros, & whatever my old Roberts had (I can't remember - Woofage, what are they?).
The Continental Super Sport was a right bugger, though. I was close to weeping once after a long solitary roadside battle to get a 25mm Super Sport onto the same MA2 rim that I later thought a Gatorskin was a doddle (comparatively) to get on & off of. Bruises, grazes, etc. I've broken tyre levers on them.
I must admit to owning & using a VAR tyre tool nowadays, bought because of past troubles. It is wonderful.
MTB tyres are mostly a piece of piss, but beware road slicks. I have a pair of old Michelin 26 x 1.5" tyres which will never again go on my MTB, because I can't face the pain. Mrs B's rims are easier, but they're still a nightmare. Her current Conti Double Fighters (26 x 1.95) slip on both her Bontrager & my rims easy as something well lubricated & stretchy, as do her old Conti Mountain Kings (26 x 2.2). In fact, I think the Mountain Kings are a little loose.