I'm probably missing something, but why do you want vertical dropouts on a commuter frame? It seems to me that the only thing that they do is to make it harder (and/or more expensive) to use an IGH if you should ever want or need to do so. And eliminate some frames from consideration. As far as rear fork ends go on a commuter, my preference (in order) would probably be 1. sliding vertical, 2. horizontal, 3. vertical, 4. track ends (only under duress as they make it more difficult to change a tire with fenders).