I have two 600rt units and the st-e3-rt, expensive set up, but it's slick!
You going to get any 440-RTs when they come out?
No, but I might pick up another 600. I had two 430s that I sold with my 580 and 50/1.4 to help cover the two 600s and st-e3-rt. The 430s were great, but the lower power and lower re-sale value have sealed the deal of, go big or go home.
Reason I asked was I have a 600-RT, an ST-E3-RT on pre-order and I was planning to get a couple of 440s when the the time comes. Basically replacing what I had (1 580 II and 2 430 IIs). Was curious if and why you were going with 600s over 440s and see have answered that.
It seemed silly before to have the bigger flash 580 as the trigger and the little 430s doing all the work. I think the new set- up makes more sense, albeit more costly.