SP-Tech says delivery dates will not be impacted. This means that hashrate will be constained by the 2400W power envelope; power supplies have already been qualified.
So if, for example, the chip needs 0.8W/GH at the system level then the SP30 will be a 3TH/s box drawing 2400W. If it is 0.6W/GH then you can have 4TH/s in the same box.
Reading this brings back memories.
They are quoting best case power estimates and guess what, if they don't come in on spec, the power supplies chosen won't be able to handle extra capacity so they'll have to completely redesign the PCB and the box will end up running slowing at the same wattage.
They may or may not need a pcb redesign, guess we'll find out soon enough.