The All-in-one water cooling solutions tend to be of poor quality. Even the more reliable ones don't get much cooler (if at all) than a High-end air cooler
If you'd like to build your own watercooling solution, there's plenty of forums here and elsewhere to advise you on components, cases, and how to mod them (bulding you own watercooling solution almost inevitably leads to some necessary case-modding).
I get the idea you don't want to go through that much trouble, though, so I'd like to reinforce the earlier recommendation for a Noctua ND-H14. It's the standby right now for a high end air cooler, and is about the same price as the coolermaster all-in-one you were considering.
good luck!