Aftermarket cooling is always better. In my opinion its worth it (if you can spare the cash ofc...), Mine went down from 60 idle and 80 full to 60 full, and 30 idle... and the silence is gold.

OC'ing is also better, not that I can reach that high now as I'm on vista and cant get the Overdrive to stop managing the oc so only on XP i use ati tool. As you know overdirve is very "soft" and only allows for 900 mem and 856 core, but I can run at that speed no problem for benching.

The plus side of HR-03/R600 is temp and silence. If you are changing only for some more mhz and the stock cooling noise at 50% (not even thinking about the 100...) is ok by you then dont.

Behave!