Recently I had done a bit of reading about hormones for a series of experiments I'm conducting myself.. What I gather from the reading I've done leads me to believe that "B vitamins" can be beneficial to yield/overall biomass in very low quantity's (like 5ppm). By beneficial I simply mean to offer any/some improvement. With what I'm doing, every little bit helps..
I'm under the impression that Superthrive is the most concentrated B vitiation around, Though not sure of its concentration I have read more than once that it only takes 1 drop per gallon, and I'm inclined to believe it (may even take less) and there are over 20,000 drops in a quart!! Seems to me once you break it down its pretty cheap stuff even if only the slightest benefits are to be had.
I would only use Superthrive when transplanting at a rate of no more than 10 drops/gallon. Hormones scare me as they mess with the plant's internal hormonal processes. Some pretty weird things can happen.