SeaSonic's "X series" for example maxes out at 1250W and a 1250W unit has higher price than a pair of 750W units (1500W total).
SeaSonic X-1250 1250W ATX12V / EPS12V SLI Ready 80 PLUS ...
www.newegg.com › ... › Power Supplies › SeaSonic USA
Rating: 4 - 1,327 reviews - $254.99 - In stock * 1 = $254.99
SeaSonic X Series X-850 (SS-850KM3 Active PFC F3) 850W ...
www.newegg.com › ... › Power Supplies › SeaSonic USA
Rating: 4 - 1,327 reviews - $169.99 - In stock * 2 = $339.98
Cypher, your boy can't even count.
Edit: For a list of 1600W power supplies, see here .
All, including Rosewill, are cheaper than a pair of x850s
The LEPA has 4 30A rails and 2 20A rails, with one 20A rail going exclusively to the 24pin connector and another to the 8pin EPS, so it would be a little more of a pain to use than the two single rail X850s. You would not only need to worry about rail balancing, but would need custom adapters (or cutting off cable ends to crimp on PCIe connectors) to get all the power out of it.
The Rosewill unit would be easier with two rails at 110A and 50A, but all the PCIe connectors are on the 110A rail. Again you'd need custom cables. It's also Silver instead of Gold, and costs more than two X850s.
The Coolmax appears to be the same Sirtec design as the Rosewill Hercules (and Scythe Chouriki 2), but I'd want to test that before I chose a unit like that for a machine this expensive.