i switched to twist grip on my FS bike and am now a convert. great for dumping a load of gears on the rear and trimming the front mech.
also just switched over form an alfine (trigger) to a rohloff (grip shift) and much prefer the grip shift for changing lots of gears in one twist.
some people complain that due to the setup on the handlebars they find it difficult to change gears and keep hold of their grip at the same time e.g you can keep a good grip whilst only using your thumbs to change on triggers. Cant say i have experienced this.
on my FS i have the short lizard skins lock on. They arent the same size as the twist grips and its not ideal having the steel lock on adjacent to the twist grip. because of this on my rohloff i just cut down some normal size ODI lock on's which operate just as good if not better.