This is such a great and flexible content, but I had nothing but bugs when I activated it. Like the others, I'm running BP on multisite (this is actually pretty common, you might want to ensure compatibility in your roadmap).
I received the same error when I tried to set the description limit. On the front side, in the profile page, when I navigated to the Portfolio tab it lost compatibility with my theme. All the tab designs disappeared and were replaced with nothing but ordinary text links.
When I tried to create an item, it failed. It didn't return an error, it just returned to the project entry page.
You might also consider adding the ability to rename Portfolio and Project to something else. Portfolio and projects are good, generic starting words, but, in my use case, I'd like to rename it Reviews and projects as Tea. Other people might want to call projects Photos, Images, and Portfolio Journal or something else. While I know changing them would be easy in the code, that method isn't very upgrade friendly. You plugin lends itself to a lot of different uses and having a little bit more flexibility for renaming the parts of it would be a tremendous benefit.
Also, since I was able to save a project, I wasn't able to test this - is this plugin activity stream friendly? Do new projects get recorded and does a filter get added to the dropdown filter?
Custom fields would be a good addition, but if adding it is duplicating the effort of the BP Groups Extras plugin than perhaps it may be better to just ensure good compatibility between the two for custom fields use instead of coding a new setup just for your plugin.
I've favorited your plugin cause I want to track its development. It fits a need in my community that I've been thinking about for some time.