Deskstar,
I just purchased the Al-Cu version but have not installed it yet so I can't comment on its
performance, but I can say the all copper version is over the reccomended weight limit
for some mobo/cpu combinations, if that is an issue for you.
BTW, I just lapped mine and the copper is beautiful but the aluminum sections look stained
but everyone assures me that it is not an issue.
If you get the chance I would love to hear about your before and after temps if you decide to
get one of these units. Good luck.
Strider