Li Shenron
Legend
I kind of like the proposed split between "active" stats (that you make checks with) and "passive" stats (that you make saves with).
So, for Illusions: you wouldn't make an Int save. Rather, the illusion would work...unless you made an Int check. The spell would demand that you do something active to contra-dict it, it's not something you're going to notice without effort.
Similarly with spells that, say, entangle you. Rather than make a Str save, you make a Str check to free yourself, on your turn. You must do something active to contradict it.
Even those few spells that are Cha saves right now might be better served either being Wis saves, or being flipped to being Cha checks that can negate the spell.
The only difference between a check and a save is that a check takes an action, while a save doesn't. This usually means in practice that (usually) ST are done immediately while checks are done at your next turn and cost your turn action.
But essentially they are the same thing i.e. a roll of the same relevant ability, so if some spells allow a Str or Int or Cha check rather than a save, that would be totally fine for me!
The only thing I'm really concerned about, is that the game desperately needs all 6 abilities to be significantly useful and desirable for everyone, in order to avoid the incredibly boring and lame practice of stat-dumping.