I have the s128 and I love it! So far, i've gotten my e6400 up to 3.0ghz and I could probably go further while staying under 60C (@3.0ghz I have 57C max). VERY good cooler for the price!
What's the full load temperature? If it's within acceptable limits, you might as well keep the current cooler. While not among the best, it's still very good.