Well, uploaded an old image sized to the new max limits in order to compare with the original.
This particular image has benefited from the revision by approx a 50% increase in image size due to the new limits.
However my thumb was rejected as being too big .
Unfortunately this required re-uploading from scratch including gallery choice, title and comments....what a PITA.
Also, all comments posted in my gallery have lost their avatars.
Site Toolbar Gallery notifications are not clearing after I have viewed them
I hope that these things will be fixed soon