I'm playing that build right now, it's my main character.
I like kensei more than shintao, the 2 extra action boosts are worth more than the 2 extra damage, at the least on elite raids and the longer epics.
Is there any set that adds more than assassin? +5 damage is a lot!
People grind raids over and over for a 1% chance at +4 tomes, so they can deal 1 more point of damage. +17 dps is a lot.