A great addition would be to use the gravatar image if desired for the author bios/post bio boxes, but have the caching used for the other options. Main issue with Gravatar is it shows an error on expiration headers with Google PageSpeed Insights due to 5 minute expiry.... there is no currenty plugin which provides for local caching for using Gravatar, and that would be huge "most wanted" option, perhaps to add to this plugin for a single solution for using ANY image for author bio, etc. :-)