Hey ash and gull, I don't want to sound like a nag screen, but what do you think of the nonofficial plugin revenue sharing thing in addition. I don't think you've voiced an opinion either way yet. It will give you a more constant stream of income. The larger the community, the more plugins made, AND the more plugins bought, so it'll be another revenue stream. Plugin devs could still have the option to not use the official plugin shop, so it wouldn't be a restrictive thing. They would just have that option of extra exposure and free hosting, and placement on the ranking/download list.
This would help you make more money off of users who are unable or unwilling to pay for either license model. And once again to make more money off the people who bought license in between their 2 year things. And it isn't evil, because you're not restricting users from any official features