I have to ask myself whether the cost of the Pro membership is justified in terms of what I want online?

I suspect that the simple answer is "No". My way forward will be to delete all but the more recent photos, and stay free.

I joined Flickr in 2005 as a Pro member. Along the way, broken Flickr systems, etc., I dumped the Pro membership. Most of my photos pass through my phone or iPad on the way to my blog, so it was convenient, as a third backup, to switch on the auto upload on the mobile devices. As a result I now have thousands of private images, as well as over a thousand public ones.

Most of the recent shared photos are IFTTT/WP shares, linked to my blog. Even the way I do that is changing, so maybe I'll just close the account?