I'm going to abandon the idea of sorting users by rank. Instead, merit will be the main criterion.
What do you think?
Over 250 Merit - 0.00008 btc/post
Over 500 Merit - 0.0001 btc/post
Over 1000 Merit - 0.00012 btc/post
Over 2000 Merit - 0.00014 btc/post
Over 4000 Merit - 0.00016 btc/post
Up to 30 posts per week.
I'm asking here for obvious reasons (there are a lot of sexy asses among you).

On 1 hand I think it's a good idea, on the other hand it opens the door for abuse of merit.
Accounts with a lot of Merit can make alts and make push them over the minimum requirement real fast, basically abusing the system.
Not saying that people will actually do it but the door is open for it, and that would be a problem. Also, I think activity should be a factor to avoid this abuse at least a bit. Otherwise total newbie accounts that maybe made 1 or 2 popular threads or whatever, earn a lot of merit with it, and then be able to participate in no time.
Of course the last decision is still with you, the campaign manager, but still I see some problems with this approach, even though the basic idea is good.