Don't use ANY cable lock and certainly not a cable loop. You might as well use cheese.
I use a D-Lock for the frame and back wheel, and plan on getting a cable loop for the front wheel. The main problem is, one D-Lock and all my college folders are heavy enough without another one added on. If I'm ever particularly paranoid about an area, I can always take the front wheel off and do it like it says on the card that came with it. My thinking is that people aren't going to bother cutting a cable just to get a wheel anyway.