it does definitely make a major difference in your dps, but with mine at lvl 8/18, it varies fight to fight. ive had some mobs where it only procs once every 5 seconds or so...but ive also had fights where it procs 8 times in 4 seconds on my 75 monk, letting my dd procs on weapons and the stuff from the new poison quest all proc at once...and just SLAMMING whatever i hit