I disagree with the premise that small edits are a bother to the reviewers. I only recently hit 2kthe threshold (for having edits applied directly and for reviewing others) and I think the smaller the edit is, the easier it is to approve. If I see a small typo being fixed, code formatted, or a sentence properly capitalized, I can see right away what it is and approve it.
The bigger the edit is, the longer it takes to check.
I say the 6 character limit needs to be abandoned.