Flow charts have always baffled me and I have always ended up buying pumps that were too big. However, I like the idea of splitting up the 4 returns and using 2 return pumps. I would then look at using the DC internal pumps. I have read that RLSS pumps will have a variable speed controller that can be controlled by an external controller like an apex. You could have one set of sea swirls that has a constant continuous flow and the other set you could run with the controllable variable speed pump to break things up a little bit. Only concern with using the controlable variable speed pump is what kind of impact would it have on the water levels in your sump and would it cause your ato to go crazy as the power increases and decreases causing the water level to go up and down.
I will agree with the above posts that you will need atleast a 5k gph pump to achieve this with one pump and with that I think the power consumption will be pretty high. I would suggest emailing your diagram to Reeflo and Dolphin pumps, explain to them what you are trying to and ask them for a suggestion. I did this when I was building my tank.