These Heatsinks greatly benefit from a case with great airflow. Most HS of course benefit from cooler case temps, but the finned radiator HS on the AC 64 PRO really responds to additional airflow.
I have a Coolermaster Wavemaster case. Replaced two of the default case fans (cfm ~28) with two 40 CFM fans. Also removed the top I/O module and installed a 40 CFM fan (output).
CPU Idle after web browsing for a few hours: 29C vs. 35 C with the default case fans.
CPU Heavy Load (Prime 95, In-place Large FFTs torture Test runing on both cores): 44C vs 56C with default case fans.
If you plan on a high airflow case, I think this HS would be very hard to beat. If low noise, low airflow is your design, even though the AC 64 Pro itself is very quiet, it really doesn't thrive as a cooler with out good airflow.