At first I didn't thought that a competitive queue would be that bad, however, after thinking about it a little bit there's two major problems in my opinion:
1. It'll affect harshly all queues, it'll take way longer to start all kind of games with the division of "competitive vs casual".
2. If you think about it a little, you'll probably notice that win/lose rates are a kind of "superficials" skill indicatives in mafia. There's just too much to be put on the table, overly-simplifying it will make it a inaccurate indicative (when some players screw the entire team over or when someone/some people are carrying the team in the back, or even in situations where things rely on luck or circumstances) and even if we draw complex criteria, there's simply not that much people to read a lot of games and through analyze the player skill.
In other words, I think competitive ranking is a good concept, but simply isn't going to work once it's applied. At least not without a proper discussion with a proper thread made only to discuss about it and bring all kind of statistics to the table.
Now, something I really would like is a increase in the avatars size (even if just a little bit, like 128x128), the actual size is rather small and is hard to find good avatars to it...
About the new players not sticking around here...uh...
As someone that talks from experience, I think that a reorganization of the board/ homepage/ navigation system would be pretty effective. The first time I joined in I need to go over all the sub forums, see how things worked out around here and all. And yes, there's no problem here and I like how the site is.
But...
People nowadays are all about doing things fast. They probably want to enter the site and instantly get a good idea of how things work, and not dig in around a little to see. Yeah...I know...it's like...everyone is just getting lazier and more uninterested, but it's true. If in the home page you can already see the games in sign up phase, and after creating the account start signing up/ playing, it would get a little better at least I suppose...however I don't know if it would change things drastically...and I like the forum in the way it is right now...
Btw, I read some thing about making micros in fast games. I approve. It's a very good idea to attract a certain public.