The slide out tray is useful for the first build, but less useful than it used to be due to the size of modern HSFs. It can actually be a hinderance on an upgrade, and if the case is actually relying on that feature, with these large HSFs you might find difficulty in installation.
I'd say the Coolermaster CM-690 V2 Dominator was a good buy, but that also seems to be out of stock in most places. These say they have it:
WaterCooling UK: Cooler Master CM-690 Dominator
BTW the BT Shop says the P182 will be in stock in 1-2 days. Might be worth waiting a coule of days and seeing who has it.