I have successfully applied a new Gate to live vocals w/ great success.
I use them also on pre recorded backing tracks using the DAS SL9000 vrs. 2.0, but never used it live until recently.
Using Celmos Stereo EchoreQ 2.0 I can get a combination of a delay/reverb with really lush long tails but these tails really clutter up a mix, so to have the effect on the live vocals I use a Gate.
The new Gate on the C350 from DAS is super smooth and clips the tails perfectly.
I made a little mp3. to better explain it's use.
But this is perfect for tracking a vocal live.
The effect is on top as it should be and the Gate open/closes making a live vocal sound awesome.
Kicking off and on a delay after the C350 for when you really want the delay/repeats sounds impressive also.
On the Dark Side Of The Moon album you can this effect on a syntheizer solo where the Tape Echo Delay allows a single repeat before being clipped. Same idea actually as the effect is heard, but the mix retains it's clarity.