I have a set of the Emgo martini shakers on, and honestly once you re-pack them (I just did) they're not bad at all.
Granted, the initial fiberglass is completely worthless and won't last 500 miles (mine didn't). When that's gone, then yes, they're obnoxious. However, the baffles are very easy to repack, and with $10 worth of batting from your local bike shop... they're a hellua deal.
--Jaeger