Never used a drift sock but did use db's bag of rocks method, except it was length of chain, and I was on the Pierre Marquette river on a two day canoe float/camping trip.

I would advise anyone that uses any type of drift sock/anchor no matter how it's secured to have a sharp knife handy to cut yourself free if for whatever reason your chosen method fails at the worst possible time.

I always carry a razor sharp neck knife or easily accessible straight blade for such times.

By the way, a 3 ft hunk of chain makes a excellent way to slow down and not hang up on a river/lake. Of course I wouldn't want to portage it in the back-country.