I asked the same question few months back and I updated the thread with my experience here http://sajha.com/sajha/html/index.cfm?forum=2&ThreadID=111786

People recommend not to have transit in European countries with travel document as some of those countries require transit visa for people without greencard and valid visa in their passport. I travel through middle east - Abudhabi and there were no issues at all. In fact, US process all people through their immigration/custom location in Abudhabi airport, so when you land in US, it will be like a domestic flight. You just need to collect your luggage and you are all set.