Hello, thanks for your interest!
The demo does not have any other difference to the full release beside the inability to export your character.
All the features yo've mentioned are already planned for Mannequin, but we do understand that because the app has taken so long to update you've became not convinced to support the development.
Currently Mannequin is basically being rebuilt from scratch for its 0.2.0 update, so the progress is inevitably long (and already delayed multiple times because of our day job and other things), but it's close. We recommend to check out the store page at the end of this month (when 0.2.0 is very likely to have released already), try out the demo again, and then judge it by yourself.
Best regards.