The Karma system doesn't seem to sound all that useful IMO.
Frogboy said about a week ago they were looking into a personal banlist in game. You ban them, they never join again so really, there's not a whole lot of sense fighting it. Use it or don't it doesnt really matter. Someone will make a working one similar to DotAs and it'll be a done deal. Whether it's in game or third party, its coming.
Again, a personal banlist is just that, personal. It pertains to one person. Not a giant issue. If you get banned for being a twat than that's on you. Maybe you shouldn't be a twat. If someone bans you for whatever reason they want with no merit, is that really a person you want to play with again anyways? He just saved you the trouble.
Approved banlists (global) come from things like TDA. A private sector of DotA made to stop leavers and things of that nature. There are set rules, if you violate them you get banned and everyone with banlist will get that ban globally. If you fucked up in TDA you're a huge moron and again, you had it coming. You chose to play in a private league and you chose to fuck up, you deserve that ban. TDA bans require a replay to prove the ban worthy so you have no leg to stand on.
So, once again. Personal bans, not a huge issue. Global bans not a huge issue.