I'm not really sure how anything in this game could be considered pay-to-win.

My reasoning is this:

We're supposed to be working together to overcome objectives that are designed for collaborative play. In this case you are not winning anything, you are supporting the team effort more effectively.

However some people like to solo stuff. In this case you are able to accomplish your objective more effectively but nobody will see you do it (unless you youtube your dungeons) so nobody is likely to know or care. Still doesn't seem like winning.

If you go into a tavern brawl it might be pay-to-win but given the disparity between classes and races I doubt that would make much of a difference.

Now think about the up-side.

I never raid. The idea of running a raid over and over again for a tiny chance to get something awesome just isn't appealing. However if I had a much better chance I might run a raid once or twice per life. If other people are like me, and I know a bunch of people who are, then you might get more people in raids more often.