Hi
Nice to see that you like our development efforts :)
There probably won't be a feature to be able to share different
folders the way you mention. Although you may be able to share
different libraries and share them to different users in the final
version.
The reason isn't that it's very hard to make this kind of
functionallity, but rather that the queries made to the database are
the exact same queries that you make to a local library, and there
isn't much use in setting access to different folders on a local
library. There is also a overhead in checking the users access all the
time that can slow down the queries.
This does not mean that there won't be a feature like this in the
future, I think it just comes down to finding a developer that is
interrested enough to develop it.
mC2 still has a long way left before we will see a final version :)