This could get broken fast. Especially since we do not allow stats over 10 for the crazy jump in levels (IE: the gap between 10-11 is equivalent to the gap between 8-10).
I myself had a limit break that gave me crazy str and speed boosts as well, but mine got hacked down to a +4 to each, and even then if it ever goes above 10 it always goes up +1.
Unfortunately, I would need similarities to this one as well. Ill allow the pump of MP+STR=X, but if it goes over 10 it would HAVE to go up only one every time.