I was considering a different and in many ways simpler tweak to non-leathal rules. Basically, I'd keep the rules as presented in the book, but change it so that you don't need to do CON damage in non-leathal in a single hit, but in a round. At a character's initiative, their non-leathal damage gets re-set, but if any time before then, they take non-leathal damage equal to or greater than their CON, they have to check for knockout as in the rules.
This way it simulates that someone with multiple attacks in a round can knock someone out, without needing the brawl feats, or having a lucky critical. Also, multiple attackers can beat someone down non-leathally.