Rated 5 out of 5 stars
It looks like I have to buck the tide and give a good review. Having given up on custom personas being fixed in my lifetime, I worked up some userChrome substitutes. Restarting Firefox for every test was a drag, so I went looking for help and found Stylish. For my limited use it was as good as I could ask; copy/paste the userChrome files and they worked immediately!
At a guess, the many unhappy reviewers were long term users of the older versions and didn't respond well to the changes. It has happened to me on other add-ons in less than 2 years using Firefox, so it must be the nature of the beast.
Anyhow, thanks to the developer for this really useful add-on.