I think the openness of Twitter -- even with it's flaws -- for this kind of discussion outweighs other means for the discussion. e.g. even if TanglerLive worked properly, it's a closed system. The fact that Tangler has a Tweet capability for messages says something doesn't it? i.e. if evangelism is one of the goals for these talks, then the more open it is, the better.
The limits of Twitter messages is both a boon and a hinderance. It forces people to make their point quickly. I tend to get long winded if given the opportunity :-) and I did notice my messages were much shorter (out of necessity) on Twitter vs. Tangler. That's not a bad thing.
It can be hard to track the flow of the conv on Twitter, because you're not guaranteed to see all the message. I did not see any of Jim Holland's messages. I was just using a browser and not a dedicated twitter client. And even across clients there are issues.
At least one person should be commissioned to retweet key messages, particularly when people (like Jim) are not visible in the main stream.
One suggestion I'd make is to promote the talks on Twitter via other hashtags. #innovation is a great one. Very active and full of people with similar mindset.
I like the Skype (voice) option for speaker orientation. That's a great back channel to keep things coordinated and flowing over the Twitter chat. I wasn't following the skype chat at all during the hour.
Again, thanks for the opportunity and I'd love to do it again if you need someone for another talk.