I think I like the current mechanic of Sky Blitz and disallowing multiple castings in a single turn, but regardless:
I think even if Dive were to be changed in the way Essence explained (which would be fine with me, I think I would just rather see it how it is), I think SoR would still have to remain. There are more skills than just Dive that seem broken if you could use them 3 times in a turn (antimatter, black hole, earthquake). None of those three would be particularly hard to pull off, and then you still get the continuing already very powerful SoR effect of being able to use the ability every turn for free. I do like the idea of self-quinting an Anubis or Aether Nymph, but I think SoR would still be overpowered if you could use them to cheaply get 5 extra Antimatters in a match, compared to now, using a single Purple Nymph.