Adding my urgent vote for this capability.
I hadn’t noticed that custom backup naming was not possible when I did the evaluation, and now I’m finding it almost impossible to use EmEditor in my workflow where I often have other scripts that process files using exclusions to ignore specific backup naming patterns.
My preference would be two-fold:
a) have the choice of whether to use multiple numbered backups or just a single backup
b) to have the choice of naming conventions such as:
file.ext in folder xxyy