I keep evolving with using your amazing plugin! I'm working on it since a week and I really love it, i really love the idea, really love the template which let us customize the views, but i'd like to suggest a few things.
The only hack i had to do in your plugin is about email templates. You should consider to add a new functionnality to let use customize the e-mail formatting and content. I had to rewrite my own functions for each cp_send_mail actions. It sounds pretty bad, because even if i backed up the changes in a an external file, i will have to redo it on the next update ..
I also made a lot of changes about how the plugin work. I didn't want my users to see content or items included in a project that they are not assigned to. I had to make changes in the activity streams.
I also added the possibility to comment the files, and i changed (without hacking core plugin files) the notifications (i wanted comment notifications, or all others ones, to be sent to all users within the project, and not only the assigned user.
I also added some functionnalities to send a mail X day before en end due date, to the assigned task user.
I also did integrate the front end with the Theme Login front end to make a real customer workspace.
I strongly recommend that you separate admin templates, and frontview templates.
If you modifify front end templates files, you don't want the admin templates to be change on the same way. And if you upgrade the plugin, the admin template is a way for the webmaster, to see what are the new changes and features with your plugin.
I really think that allowing us to modify in the same way, the front end, and the admin templates, is a complete error. You should seperate the templates, or not allow use to modify them.
Well, if you'd like to see a screenshot of what i did, check this: http://www.thomaslartaud.com/docs/collabpress-custom.jpg
This a plugin is a really great one, and should really deserve to become a premium one, as soon as all the functionnalities are functionnals (like: completely trasnlated, more options for permissions, mail templating, no admin template re-writing, add comments to files, [add stick notes custom post type], etc, etc .. )
Bye, and thanks for your work!