I don't have a link, but have done a lot of research on these.
I remember reading that the cooling efficiency is almost equal.
The all copper one weighs much more than the Intel spec for P4 mobo recommends.
Edit: I checked out that link, was a very nice comparison.
This quote tellls the tale: "Not much different between CNPS7000A-ALCU and CNPS7000A-CU" (the poor grammar is theirs)