As an avid user of 2D Tool Kit, I would have to advise against DLLs. My company purchased the plugin to convert our existing games into Unity and since then it has been a wonderful process for both Art and Programming. The Artist enjoy all the great features it has such as Dicing and previewing animations. The programmers enjoy the plugin because it's open source and they've been able to extend it for our specific needs. For instance, I began researching how to "mask" or "clip" sprites and I didn't like the hard edge solution that I found on the private forum. So our programmers wrote a Shader base clipper that allows "soft edges". They stated that if this was all DLLs then it would've made life much more difficult and we wouldn't have purchased it. You still have to consider that people will need to customize and extend the plugin according to their needs.
I also have 2 more questions:
1. When we do upgrade, whats the best procedure to do so? Once again our programming department extended the plugin and we don't want to lose any of the scripts they've written.
2. Where's the best place to submit suggestions for additional features? As the Art Director I have an extensive background using After Effects and the I'd like to see some of the standard Time Line features, such as scrubbing, added to the Sprite Animation window. There's a few other suggestions I'd like to make that would greatly improve the workflow, but I want to submit it to the right place.
Thank You.