I do make adapters that would allow the for the use of 1200i PSUs with Neptunes and most likely Titans, Searing. It just uses two PCIe cables instead of one and that bypasses the over current protection.
Definitely cheaper than buying whole new sets of PSUs. They are in the wild now and no reported issues so far. Check my post history in this thread for a pic.
Just to say I've been running the PCIe 2-to-1 cables (that I bought from Cablez) on my Neptune for just over a month now. With the cables, my Corsair AX1200i PSUs work great. I'm running at normal speed (475MHz) and the Neptune is hashing at 3.4TH/s. The cables aren't getting warm, which is a good sign.
As a note, I was running three modules off one AX1200i, however I've bought another AX1200i so that at max I run two modules per PSU. The AX1200i that was running three modules did power off once (in a solid month of running), which I think may have been due to too much current being drawn from it.