Hello fellow Belgian
First off: Don't go for the corsair. I'd wait for the new Swiftech H220 to arrive and see how it's priced.
Secondly: How high you can run your CPU with certain cooling solutions will largely depend on how much voltage it needs to achieve that speed.
A big bulky air cooler might interfere with tall RAM memory as well. So that's a plus for AIO and watercooling sets. Other than that, a big air cooler is better price / performance wise.
PS: sent you a PM
EDIT: Perhaps a plus for air coolers is the extra airflow around the VRM heatsinks of the motherboard. Additionally, I find it much easier to make a very silent rig using air-cooling, of course not with the same cooling capabilities of a custom loop.
In regards to watercooling leaking and maintenance: If you use a silver kill coil and / or some kind of biocide you shouldn't really replace your water. You can clean the whole loop every 6 months / yearly to check for algea or other things though, and I'd actually recommend doing that. Tubing etc lasts pretty much as long as you want it to.
So far I've had 3 leaks:
1 time I didn't put a stopper in one of the ports of my res ... doesn't really count as a leak due to usage but more stupidity ^^
Second time I forgot to place an O-ring, again, stupidity rather than wear or anything like that.
Third time it was actually a rotary fitting that leaked ever so slightly. It was due to stress in a certain direction. I'd shy away from using rotary fittings as much as possible if they aren't needed.
Extensive leak-testing while filling and bleeding + regular check-ups will avoid most problems you might encounter with watercooling. With a kit like Corsair's you have a false sense of security IMHO.Edited by Bloitz - 1/24/13 at 4:03am