Again, ANY solution that has Auxin (Indole3 Butyric Acid or Indole Acetic Acid) will work. I don't see the benefit of the added B complex. If ya want a name brand, about the ONLY MG product I use is their "Starting and Rooting Solution" at a dilution of 1/4 recommended strength. I use the "Green Light" brand of rooting powder to root clones.
Superthrive gets rave reviews, I don't see it for the cost.
I re-read my post, and I don't see where I said not to use anything. I just asked why you thought you needed the added B.