All three Nitro are now available to pre-order on OcUK.
The Nitro+ OC 8G shall increase to £259.99 inc. VAT tomorrow at 18:00, so were giving you plenty of advance warning and regular Nitro shall hold at £249.95
At this rate the Powercolor is the better deal with a higher clockspeed as stock.
I'm waiting until reviews but not likely to go for the Nitro after the price increase. It's obvious the standard Nitro will be a lesser clocking chip.