I have no idea why either - Alphcools products of late havent been that great.
XSPC radiators are getting a great rep - they have been shown to beat black ice and swiftech (and alphacool since they are rebranded older revisions of black ice)
If you want performance, its Thermochill - price vs performance XSPC are looking hard to beat at the moment.
Fuzions should be back in stock in the UK next week