I have one for my siphon—filters the grinds perfectly well, but as others have touched upon, it’s a bit of a chore to keep clean. In addition to cleaning after each use, I boil the crap out of it every now and then for extra measure with a touch of vinegar and it seems to keep it clean.
I still use paper filters for my v60 and I’ve never used the coffee sock on it. Maybe I’ll give it a try.