For what it's worth.

Bladedancer: it is great but imo is kinda in the spot Bloodstalker was. It has the best ST dps BUT on fights with Disconnects it is going to suffer more, just like Blood stalker did. The upside is that is also does pretty darn decent AoE dps so it is not a one trick pony, it's a two trik pony.

Marksman: It basically takes the place of ranger...still have yet to work a ranger build that does more dps than a MM build (though some equal it) ST and there is no annoying pet to die and take a chunk of the dps with it.

Nightblade. Some people pooh pooh it. The energy issue is annoying as hell. Try as I might though my parsse difference on a dummy between NB and Bladedancer is always between 200-300 dps. Add in Fervor or clover, and Nightstalker and the difference does narrow in a real fight. With the ranged option it has it is also MUCH more friendly on disconnects. So I think 51 NB will be in the same spot 49 NB was in relation to BS. Fights with disconnects, NB, fights where you can plant and churn out the rotation, BD (in place of bloodstalker.)