I also think certain skills don't work when the mob is in the air - or are harder to pull off. Some elites don't seem to move either. The effect lasts for 5 seconds and most elites are dead in 5 seconds with the 1x monk and 3x crusaders zDPS, exploding palm build. I do use strongarms on my monk for sure.
http://us.battle.net/d3/en/profile/K.../hero/30050343

I tried this on my crusaders at one point (who don't have near as many knockback effects), It seemed better to just do 20% more holy damage and reaper wraps. I must have like 12+ pairs of strongarms.