Sweeeeeet. You even did it the right way and tested all the heatsinks in a case. Most sites don't do that. And as you know, coolers always perform better inside a case. (assuming the case is well ventilated)
I have only one suggestion: use the same fan for all the tests if possible. The problem is it's really really hard to read the results in the test results when you use multiple fans. I developed a headache trying to decipher the results between say a stock AMD HSF and HSF's that were benched. Some may disagree with me on this point (esp. those who are curious to see results with other fans), however using the same fan does not diminish the actual cooling results of the heatsink. In the end the results of cooling capability should be the same. Yes, adding a more powerful fan will lower the temp, but this does not say anything about the heatsink itself. You might also try splitting up the charts. Have 100% on a completely different chart from 50% fan speed. This would certainly aid in the reading of your results. I noticed that you sort of did that in the end of your article... but it would be nice to see it split up more. Does that make sense? It's just my opinion and I could be in the minority.
Thanks!
-mpjesse