Coming in late on this one.
I don't think debating has to be abusive to be effective. IMO once it reaches that point it's no longer debating it two people bashing each other over the head with their entrenched viewponts. Course I'm not gonna lie, I'm as guilty as the next person of being drawn into that kind of pissing match. All it did was make me feel bad, certainly didn't change my opinion or open my mind to any new ideas which for me is what debating is all about.
Couple of things I've learned thru the years on discussion boards. State your views, be willing and able to back them up with facts, keep an open mind yourself to others viewpoints and show them the same respect you would like to get, be ready to walk away when you realize it's futile to continue the discussion. Oh and it's ok to say "Dang I was wrong".
I generally tend to ignore people who talk trash to and/or about me. People who know me know the person I am. People who don't know me will either take the time to get to know me or think the worst of me based on something they read online, guess which person I care about. That said I do at times feel the need to confront people that I feel are abusing myself or others, everyone needs some type of accountablity and I pick my battles.