I put stuff out on the curb last weekend and it was gone in an hour or so. I just need to empty it, put back the stuff I want to keep and throw out/give away everything else. It's a monumental task.
Gate valves are repairable should they fail, ball valves aren't. 2" isn't nearly enough to drain 4300 gallons quickly. The two 3" gate valves would be for emergency draining in case of tank failure and in progress flooding of my houseThink fire hydrant flow rate...
3" gate valve is cheaper too as I'll be buying in 6+ lots http://www.aquaticeco.com/subcategories/2513/Knife-Gate-Valves-1-1-2-to-8/gate valve/0
Though, I may have to use ball valve, as the one I just listed is for low pressure and we will have extreme pressure on these toward the bottom of the tank.