@Brendanjones You make a good point that familiarity is helpful. i.e. I don't have to relearn something from scratch. The point I was getting at is that it's not enough for the open experience to be the same... it has to be fundamentally better to motivate people to switch.

This happened with AOL vs. the web. When really cool web sites emerged that were far better than anything AOL could do on their own, people switched. If the web was just a carbon copy of AOL, nobody would have switched.