Previous profile configuration lost when assigning different editor

Hm. Yes. I also thought about this a few times, but unfortunately, didn't come to a conclusion. Another possible approach would be to store the configuration per editor, for each input format. So if you change the editor to editorB, the configuration for editorA is kept. If you select editorA for this input format again, the original values are back again.

But then again, another consideration was that an admin might want to use the editor configuration of one input format in another input format upon switching the editor. I think that's the most common case: You set up a profile for "Filtered HTML", and later decide that the default input format should not have a full-blown editor. So you switch the editor to another editor, reconfigure the profile for "Filtered HTML", and ideally, you would like to assign the previous profile to "Full HTML" or whatever input format.

The latter would require that an admin is able to setup editor profiles first - regardless of input formats and associations. Afterwards, profiles can be assigned to and unassigned from input formats.

Well, yes, but that's slightly offtopic. Forms can be displayed, submitted, and processed anywhere in Drupal, so the location does not matter for this issue.

Thanks for reporting! Committed attached patch to all branches.

A new development snapshot will be available within the next 12 hours. This improvement will be available in the next official release.