Now that I think about it, if you have multiple sumps at the same level, they need to be plumbed together. Otherwise, if one pump stopped, but the other(s) didn't, that sump would overflow and the other(s) would end up running dry. Maybe they covered that in the equipment forum.
I personally don't see the benefit of having a separate sump and fuge, unless you have a difficult space restriction, or are doing something like me, which is having an above tank fuge, but a sump that's lower. If you can have one larger sump with the return in the middle, then you avoid the hassle and potential leaks of (multiple) bulkheads to connect the sumps.