I disagree.  I think you're asking for trouble running the PSU at 100% or more than 100%.

The D3 uses 1200W "at the wall", right?

From my experience running the 2400w PSU at 100% may work for a short bit, however the PSU will scream like a jet engine the entire time.

What you could do is use three PSUs to power two units.  Just make sure you don't mix and match power sources to each hash board.

M