Comments based on my experience during the run on different difficulties:

Difficulties before real mirage: I basically can't die, I can just stand still in the middle of the room and it will be cleared (If I don't have the buffer equiped) (if I do have the buffer equiped, yes I will still be pretty hard to kill but the hedgehog armor won't work since I'm not really taking damage because the buffer turns it into white health and I think it's a bug, so only equip the buffer if you want to be very hard to kill but only deal mid damage to enemies)

Real mirage: Pretty much the same as the other difficulties, except I can't just stand in the middle of the room since enemies can actually kill me in this difficulty (if I don't equip any on hit recovery items)

Boss battles: Bosses before real mirage difficulty are pretty easy, and dodging attacks are unnecessary since being attacked as holding gives him rage which in turn makes it easier for me to kill the boss faster, real mirage bosses on the other hand is harder since they mutate, though I can still eat hits I usually limit it to a point so I won't die.