Actually a spec more like
http://www.wowhead.com/?talent=j0xZhxet0ebohRMocxcg00x0o would work much better.
Granted my "hybrid trispec" which is more like
http://www.wowhead.com/?talent=j0E0VZhxet0ebohoZcg00xco is what I use for heroics / raids where I am acting DPS / OT.
I like to shorten the CD on DnD for the start of pulls or when general adds come around, granted this will be changed when pestilence loses its CD due to the fact that Pest + HB (if dots on main target already) > DnD for snap threat.