I tried for years to figure out why I could never actually hear single pitches when I played col legno on my viola. I also wondered why my pizzicato notes often sounded so "papery," but the actual reasons I decided to try a new tailpiece had to do with things far more practical. My left wrist and my G string peg did not seem to want to work together to bring the string to pitch, and the strings I like to use (Larsen) happen to be a little thick for the holes and slots of my old tailpiece. My instrument would also rattle when the balls of the strings would buzz against the wood of the tailpiece. I decided to modernize, and I got a tailpiece made by Les Bois d'Harmonie.
All my problems are solved, and my instrument sounds far better (when played with the bow normally as well as when playing pizzicato and col legno--with wood of the bow) than it ever did before. I can also make a sound in ponticello (playing on the bridge) that is not ugly.
Notice that the strings do not actually contact the tailpiece itself, except for the places they connect with the fine tuners. Perhaps this is one the reason the instrument feels so free. The fine tuners are made of carbon fiber, and they are very snug, so no matter how much vibration comes their way, they do not rattle.
And it is a very beautiful tailpiece.
These tailpieces cost a lot more than standard tailpieces, but, over the long term (the life of the instrument), the extra expense is worth it.