I agree to a point that there is no difference as far as making it cooler.
Though, reg load temps are the same for me, but the AS5 on my stock P4 setup, has dropped at the most 3 degrees C at idle, compared to my reg thermal paste.
Other thing, hard to say, it may drop the temp faster then thermal when the load is off it. Can't verify it, but for me just seems that way.
Now, for me.. it really doesn't justfiy why I spent 11 bucks at Compusa for AS5 VS Radio Shack tube thermal compound that I had for over 5 years for 6-7 bucks. I was running low and thought.. what the heck. 😀
I dunno... whatevah trips anyones triggah. Can't find out yourself till you tried.