Your/their assertion that it is 80 Plus certified is not true. It is not certified.
Can you see 'Powercool' on this page?
http://www.plugloadsolutions.com/80PlusPowerSupplies.aspx
Because I can't.
I would suggest avoiding it because it hasn't been tested by a competent reviewer, or any reviewer at all, that I've found.
If you really need a 1000W unit then that unit doesn't fit the bill because builds that really need 1KW units need more than two PCIe connectors. An ~850W unit in the £80-90 price range would perform better than that Powercool if you do really need a 1KW unit. If you don't need a 1KW unit then you'd be better off getting a 'lower wattage', but higher quality unit.