"The Ubuntu people seem to have recently pushed to users a new version of the CUPS printer scheduler"

If you don't like breaking changes then you might consider using an Ubuntu LTS and then adding your own changes as required.

I've been using CUPS for roughly 20 years and since I ditched HPLIP and the like some years ago and went all in on IPP Anywhere, its been rock solid for me at home and at work and for quite a few customers.

So, which version of Ubuntu do you rock and can we have some links to discussions please? Or some idea of the issues involved.