I main a sage dps TK for HM progression. They are extremely good (like all classes) in the hand of a skilled player. Main advantage: TK is easy to learn, rotation is easy but gearing is a pain since you aren't supposed to use any crit rating.
It has some great tools for an operation group and shouldn't be overlooked.
In terms of raw damage, it isn't the highest at the moment but you can still be competitive. I parse around 4600 with mine.