I am currently using the stock cooler.
My temps before the water cooling were 49 idle, and that's why I got the water cooling. However, I had my motherboard outside of my case and I tried to mount the stock cooler again and realized that I had originally not mounted it flush against the cpu. When I turned on the computer I was getting 36 idle. I was quite angry, because this water cooling set up seemed like a waste.
However, for someone like you who does a lot of overclocking, it seems like it would be a great buy.