As long as i get to be the frog
Again, in regards to what I care about it’s all still magic - and whether it’s spellcasting or supernatural mythical abilities, both are the equally not wanted on fighters by me and many others.The difference is that the mythic is defined by his abilities, and can use them (and slant-use-them) more freely, but can't change them. The wizard can change their spells each day, and so gains way more flexibility.. but that flexibility should come at the cost of raw power. Let wizards/full casters be the heisenwizards, let the mythics be the superheros.
Edit: see also the Hero system.
Also of importance - mythical fighters and non mythical fighters will never be fictionally workable in the same game. The moment the non-mythical surpasses the mythical at combat (as would be required for any semblance of balance) the mythical stops fictionally being mythical.