There's no reason I can think of that you would need "all those pumps". A single return pump would do the job, just split the return line and put in ball valves so you can control the flow rates into the different tanks.
The downside of this is only that if something goes wrong in one tank, it would afect the other as well. The upside is that there's less stuff to go wrong. I know that if I got "into" this hobby more and had the money to do it, I'd plump all my diplays into a fish room where the sump/refugium/RSB and all the equipment was housed.