That's what I find so disconcerting about websites such as this. Granted, it is more likely to happen here then on other sites given the nature of the discussions. Yet you get to know people a little bit, albeit not person to person. You talk to them and sometimes argue and then they disappear without a trace.
You are right, Ed has not posted since early december 2015.
Let us hope he is okay and will return to the forum soon.