Personally, I think the "perks" idea would be best. Just offer a like $4.99 membership monthly thing, and have some servers be members only, some servers be login only, and some servers be generic pub. And on the server list it could list the type of game type (member,login, or pub). You could do little things like as an observer you can see the players name above there head at all times, and do the custom jerseys idea. Also if your in a clan, and a member, you could do the "submit clan symbol idea" and put custom jerseys for people wearing the clan tag, and logged in, and members. This community would definitely supply the members because its really supportive, and would probably become a member not for the perks, but because they want to support the game.
Also, if you do make a membership thing, I suggest that if you are a member you can choose between like 4 player models, some being girls too, so that way you can show off your membership with a sweet new model, custom clan jersey, and such. Also newer players on the pub servers would see you and be like "how do you get that model" and then the member would be like "go become a member and all your dreams will be realized"
This would be the easiest way I can see to gain revenue. You could also crank out the ads on dplogin.com to make some extra dough. I know I would click on the ads just because I knew it would fund this game.
Consider these thoughts,
Cusoman