Make a group from the same server doesn't have to be an all or nothing situation and doesn't even have to be an option people pick. Blizzard already looks at a number of factors when making the group with the RDF, with a new one coming with 4.1. A preference towards grouping people from the same server could be another. If it's off hours, or lower level or just not able to find people from the same server it could still mix people from multiple servers.

Short of heavy and quick gm intervention for petitions about DF problems, the only way to get people to behave better is to remove at least some of the anonymity of the tool. People don't care about their behavior because they know that the chance of it having any impact on them is almost 0. That has to change to get them to change their behavior.

Personally I fall into the Mercenary category but it's on my alt dk. I consider dps his main spec but have had a tank spec for him pretty much from the start because it made groups so much easier and in the end made gearing up his dps spec quicker and less frustrating. I don't know that the CtA rewards will get me to tank many extra dungeons just for them but the change to 7 a week will probably get me doing a fair number more. Generally, I've only got 2 or 3 days a week where I have enough play time to do my mains DF run and then my alt's but i could easily see doing a few more for him on a day where I do have more play time.

Reply