Go with the Ninja or other high end heatpipe cooling: Thermalright Ultra 120 or Thermalright Ultra 120 Extreme, Scythe Infinity, Tuniq T-120. There's a review showing the CM Aquagate Mini R80 about equal in performance to a Thermalright SI-120, which the Ninja and other heatsinks listed above will easily outperform all while remaining simpler to install, costing a little less, making less noise (no water pump) and having fewer possible points of failure.
There's a particular reason I like the Ninja more than the others (the Thermalright Ultra-120 was on my short-short list too) even though some of the others may be able to get temps a couple of degrees cooler: weight distribution. Examine the Ultra-120, and the Tuniq-T120, and even the Scythe Infinity and you'll notice there's a lot of material hanging out a good distance from the mobo. The Ninja weighs close to the same as the Ultra-120 but notice the Ultra-120 has almost *no* material down at the mounting point - just a contact plate. That means almost all of its weight is cantilevered from the mobo. The Ninja has a chunky piece of aluminum sitting over it's contact plate and then only about 24 fins that project out away from the mobo. So it's my estimation that the cantilever force on the Ninja is much less than the others base on these observations.
Add to that the fact that you can actually mount 2 fans to the Ninja in a push-pull config for some additional cooling power.
Add to that the fact that the Ninja is designed from the start for quiet cooling - large fans at low RPMs.
Good cooling boils down to this (no pun intended): how quickly can you distribute the heat away from the source and spread it out over the largest possible cooling area in order for it to be dissipated? Heatpipes have proven to be amazingly effective at quickly transmitting heat from one place to another. Water cooling works basically the same: think of the water tubes as heat pipes. The difference is that a water system will have many times the thermal mass of a heatpipe system and so will take longer to warm up. But once it does warm up its all about how fast that water is moving and how broad of an area it distributes the heat to. The Aquagate Mini R80 doesn't seem to have any more distribution area, probably less judging from appearances, than these high end heatpipe heatsinks.