My buddies down at the Hydro store tell me that Gravity works pretty much the same as Over-Drive. I hope it works better then that for the money it cost. $35 for 8 OZ's.
I am thinking of buying the Purple Max for my Clopnes I just drop into flowering cycle a week ago. I have heard good things about this also. But I am still going to go very, very slow with anything from Humbolt's product line.
Peace you guys and good growing.