IF you get two Gold rated PSU it is unlikely you are saving that much. Two PSU is simply an extra component, more space, more potential failures.
Not saying it is impossible but to make your rig more complicated to save $40 and (as OP indicated) do so at reduced efficiency just doesn't make any sense to me.
Then again I got 5 rigs to manage so I like them .... simple.
Of course - but if you are aiming for 50% load, as well as running 6 5870's in a rig, you have to either get 2 PSUs or pay a stratospheric cost for a single 2000 watt PSU