Cloning a HD vs. Copying Files - Which is faster?

Cloning will be much. much faster. I cant say how much, as it will depend on the speed of your setup. However, it shouldnt take more than a few hours.

Copying has to open a file, read it, write it, and then close it. Virus scaers will look at every file you open, as well. Other file system based hooks could slow it down, like indexing.

Cloning simply reads and writes bits. Nothing will slow it down other than disk usage.