If you haven’t checked out the CCK2 lately, you should.
One of the coolest features I’ve added recently is the ability to hide things on any arbitrary window that is opened by Firefox. For instance, if you want to hide the bottom box in the about dialog, you can add “#aboutDialog #bottomBox” to the hidden UI section. You can also use it to hide arbitrary content in about:addons. I’ve also done major work on the clipboard capabilities API, so it should be more robust. There have also been quite a few bug fixes. You can keep up on all the latest changes here.
If you want to request a feature, you can do so on the CCK2 support site. Priority for any requests is given to paying customers.
And if the CCK2 saves you time and money, please consider getting a support contract. It ensures that I’ll be able to keep working on the CCK2.