I have to agree that there should be no "Only with extra limbs" limitation on the STR, since the extra limbs are in almost all ways superior to the regular limbs. About the only thing he'd lose is leaping, and since you bought so much of that with advantages, it's essentially irelevant. Also, since it's a compound power in the same slot with the extra limbs, it's going to be drained together with the extra limbs anyway, so saying "But the limbs can be drained" doesn't cut it.