Upload & Sell: Off
Todd, all I see is a huge waste of money (I might have it wrong). I'm not really sure of your desire to stick with the STE3RT and the expensive 600EX's when you can buy much more power for the same or less money, albeit a different system and possibly totally lacking any communication or automation. I have no experience with such gear (I shoot manual EVERYTHING all the time) so I can't comment but I do have a lot of experience with location strobes and I can honestly say that the more power you have the easier your job will be. If you go down the speedlight route I don't doubt you will come to the same conclusion. I'd also suggest culling it all down to just a few, bare minimum, items and THEN, after using it for a while, see what's missing and fill the gaps. You appear to have gone the other way and filled all the gaps before even knowing what they are (yes, I know you've researched it).
Do you realise that 3 600's will only give you about 1.5 stop more light than a single 600. You could spend the same amount of money and burn the retina's out of your clients eyes with a host of battery powered strobes (or monolight/inverter setups). The 580EXII has the same power as the 600EX. The old Nikon SB28, and about a hundred other old strobes, have the same light output as the 600 but cost about 1/4 or less. If you don't need the automation then there are MUCH cheaper speedlight options you could try out. If they don't work then you haven't lost much.