That ENTER stuff only happens (in Firefox at least), when you have only ONE input field on form and you hit ENTER while typing text in it.
This is browser auto-form-submit feature and there are not special logic in that. I've managed to reproduce it on group editing page.
To overcome such nasty effect we usually add hidden input field on each form, so browser won't react on ENTER in described way. But since there are no much forms with only one input field in administrative console, then there was no need for that.
Since all edit forms should use "inp_edit_filler" block on them to fill empty space beneath controls, then we could add that hidden input there and see how it will end up.
I've attached patch with proposed fix. Since it will have minimal impact on existing functionality, then I suppose, that it will be used at the end.
What's your opinion on that matter?