[Molly]

I liked your earlier solution better, because it is less easy to sidestep by those who have an interest in obscuring their payment model, and also because a text area won't show up in any searches.

I also think there is a distinct risk that it will not be completed honestly in many cases. When that happens it almost certainly will be noted and commented on by someone in the discussion boards, which will lead to more inflammatory threads.

If you go for this text area, at least make it obligatory to fill in, in the same way that the 'rate' box is obligatory now.

And here is a suggestion: Why not use both?
Keep the check boxes, but also give the Mudowners a chance to explain the details of their system in an attached text area.