The N520 might be OK if you have clearance issues, since it should be more compact. Just looking at the dimensions, it's almsot 1/3 of the total volume of the EVO, but keep in mind that a 92mm fan is going to have to spin a lot faster to move as much air as the 120mm fan on the EVO, and a smaller heatsink means lower total heat capacity for similar material construction. It will likely be hotter, and louder, under similar loads.
Unless your case is very tight, I'd go with the EVO.