I suddenly realised now I am here in Montreal preparing to defend my ideas against 100 experts from around the world that I have failed to notice all this time the biggest advantage of MVDs. And it is this: The alternative to computing the interrelations between multi-version texts can only be encoding them manually. In speaking of the supposed advantages of standard XML tools what is often forgotten is the enormous human cost of training people to use markup, and getting them to encode it and check it against the originals. I know from experience that this is very expensive. We literally spent thousands of man-hours encoding variants in Wittgenstein. If we could have had a tool for doing that automatically, much of that time and money would have been saved.
Another advantage of computing interrelations automatically is that it is so easy to get back what you put in, unmolested. Hand-encoded XML hard-wires the interconnections between versions, and getting back the original text can be a hard problem if you decide later to change to another technology. With nmerge I just press the "archive" button and it is done.
If computers are good for anything they are good for saving human effort.