Hmm idk that these will be much better. Aluminum sinks tends to transfers heat better to air than copper. Pound for pound, copper wins on every front - but aluminum has such a low density, you get much more surface area out of aluminum, per pound, than you can copper. And surface area is what tends to trump when trying to dump heat to air.
Usually in a radiator, the biggest factor on performance is fin surface area - the heat transfer to air. Water holds so much energy per volume that it doesn't take a lot of volume of water to get a lot of thermal energy in there, but air sucks at it, so it takes a crapload of air to be able to match the thermal load the water has inside.
Now, if they are not painted (which would hurt the heat transfer to air) or anodized, a pure copper radiator would look really cool - at least until it gets that green patina on it.
