If I plumb two pumps into a Calfo-esque manifold to improve circulation (Sump return Mag 1200 and Closed loop return mag 2400) with one pump twice as strong as the other....

Potential downfalls? Other then the one pump dying and flooding my sump, will the difference in pump outputs severly limit the GPH return from my sump?

Should I rig two distinct manifolds or am i safe with both pumps plumbed into the same manifold?

I'm leaning towards option #1 but would love a second opinion (I've already breeched my new tank budget for the week, sheesh)