peruvianus do grow faster and have a larger diameter than pedros at full maturity.
i happen to love the long drooping spines and the intense blue color.
from experience i have to say the whole potency thing is completely unpredictable. there are so many other factors than the species that determine the strength of a cutting. even two cuttings from the same plant can be different in potency. some t. peruvianus i have tried were amazing, but on the other hand some of the material i have sampled has been nearly inactive. san pedros can be very potent, just as much as peruvuanius, it all depends on the time of harvest, water content, soil conditions, genetics ect. i personally like bridgesii the best, although some can be just as weak as the weakest pedro.
remember, a lot of vendors out there do not sell real peruvianus but a look-alike called cuzcoensis. this cactus is nearly worthless for eating, i should know i own one lol. its a pretty cactus, but when i cut off a little to taste the green flesh, it was not bitter at all. i cut off a little under the skin of my pachanois and it tastes very bitter.