I had an XSPC Rad for a while, leaked but I guess I was just unlucky. Didnt think the performance was bad, but not great either. They appear to be very similar to the older BlackIce rads from what i remember. Then again, better performing options such as Thermochill are waaay more expensive, so that rad probably gives good price to performance. As Kempez says you will need more powerful fans... you might want to get some fairly high airflow fans and put them on a controller if you need it silent.
As for worm drive clips... I find plastic ones a lot better, however they will work just fine, just my personal choice as they are a bit less fiddly and easier on your hands (wormdrive can be sharp)