Maybe it would be sensible to exclude counting reverts and rollbacks, as often pages are emptied accidentally by IPs and rollbacked by Recent-Changes-Patrollers to its previous state, which would be counted as adding a lot of text.

Please add a sortable parameter on relative added text (proportion of added text of the author in the article).

Looks unrealistic to me: as it involves getting the wikiwho blame of every article the user ever edited.

This task predates WikiWho. I think what is being asked is to return the pages the user edited the most according to bytes changed, as opposed to the number of edits. As @Ghilt mentions, this should probably exclude edits with the mw-reverted tag.

If this were to become realized, the query would be something similar to what would be done for T172001. As long as it finishes in a reasonable time, I'm personally okay with it. It may make sense as an entirely different tool, with the route being /topedits-bytes or something. Or, we could add a new checkbox to form, "Use bytes changed instead of number of edits", selectable only for the Top Edits by-namepsace function (i.e. when a page title is not provided).