flow rate for the return section is set by the drain line flow rate, so is not adjustable till after the pump, which in turn sets the flow rate through the drains. Nothing different there really other than the return is in the middle section of the sump.
There is no advantage or need to have 100% of your water going through the "fuge" (in the middle in your drawing.) moving the fuge to the end of the sump gives you the ability to separate the flow through the "fuge" from the main flow through the sump, (different flow rate) and the ability to take the "fuge" offline, without shutting down the whole system. It breaks the dependency of one on the other.
Jim