By and large, the problem with the wrong feed are ones of duration and dosage. I would absolutely use the 30% feed, PARTICULARLY as you have meaties. Your concerns with those are rapid growth to table, nothing else. Well, cost - but as you already have the bag, that ship has sailed.
FWIW, most of the literature I've read puts meaties in a target range of 22-24% protein first three weeks, 2% less protein next three weeks. and then finishing at either 18 or 20% after that. I've been quite please with feeding 24% straight thru, and I believe several routine posters in the meat bird threads do similarly (and post better results than I, but they both have better starting birds, and don't free range).