I've found that cat-whiskers do a slightly better job of reduing string oscillation, but the leeches do OK. There is the cost to figure in also. Leeches cost about $9 for four. Cat-whiskers are abour $1.50 and usually outlast leeches 10 to 1. Cat-whiskers slow the bow down a bit more, but speed is something that is blown way out of proprtion for hunting distances.

That being said, most newer bows tend to be very quiet. It's usually some piece of plastic accessories on the bow that'll do most of the noise making.