CTA has failed pretty miserably for the troll heroics.

CTA has failed pretty miserably for the troll heroics (though seems to be working nicely for the older heroics). So, instead if trying to get more tanks/healers to queue up, how about trying to get less DPS to queue?

My proposal is this: For each half hour you spend in queue, you get an additional 140 vp (70 for older cata heroics) once the run completes (cannot exceed the 980/490 limit, of course). This means DPS who are just there for valor would be queuing roughly half as much.

A reasonable concern!

The actual number of bonus VP would probably have to be tweaked so it's more time efficient to do a role with a short queue time rather than a long one. Even if it means DPS have to do 1 or 2 less heroics per week, that's a LOT of dps taken out of the queue.