really like this plugin - and also the evolution it is taking :-)
However to keep it flexible and compatible with current use case I would propose some changes/ features:
1) Add a filter for the default image - thus enabling the definition of a non-Gravatar default as well
2) Make the rating something to be enabled/ disabled by the site admin - yes, it does not harm to have it...but I e.g. try to keep the sire lean towards the users
3) Make the usage of gallery items as avatar to be enabled/ disabled by the site admin as well - same as above
4) Implement "fallback" option for deleting an avatar - to make it compatible with frontend user management integrations/ themed user profile pages
In case you want, I am happy to contribute some code for making this changes happen...
Thanks for consideration!