For the past year or so I pondered over getting one and I eventually got one build into my yamaha effects rack. And man they are essential! I never realised just how useful. I set it really low down so it doesnt effect solos or that. But just in so far as when u mute strings or play stuff stacato (duno if thats the rite term, i mean choppy, without letting strings ring) its awesome!
For those not sure whether or not to get one I say give em a go!