http://us.battle.net/d3/en/calculator/demon-hunter#ehkQjP!geX!aYaYcY

I was playing around with the skill calculator, and It's looking like trap-hunters might be viable? My only issue is - how is Discipline looking? Even with only 8 discipline used per sentry, I'm a bit worried that the slow discipline might be..too slow?

Anyone in the beta who can shed some light on the Discipline gains, and if there's ways to increase it that I'm missing?