As a newer tank I let people know every time I go into an instance if I know it or not, and that I am newer. I have had more healers drop than anyone else, I am not a GREAT tank, but I usually carry my weight.

I always stick with the group, if we die once, I stay, but I ask for advice on what I could have done differently, to make the situation better. Sometimes I get information that could have helped more on the original attempt, and we try again.

I have had asses in groups from time to time. As I made it clear at the start of the run that I was new, I don't feel too bad if something happens and people are willing to give constructive critisism, but when people are negative, well I wont re-queue for days or weeks. (I love to play alts)

I play this game for fun, the new rewards might reduce the queue times for dps, but if people still don't want to queue as tanks because the "Bribe" to deal with asses isn't always going to be enough. The reality is, if I get into a group with those guys, I will probably still stop, and run maybe 1 or two dungeons a week, and then only when I want to take a break from leveling an alt.

I think extra incentives is a nice thought, and even dps will have the ability to get the rewards, (mind you I don't ever see that happening), but it is just a temporary solution to a problem, as there will be a limited amount of items, and once every mount, pet, etc is collected, the incentive is mostly gone.