Robert, I think the example you are concerned about is fairly
contrived so I think I would be perfectly happy to have it be
quite clunky to do. Offhand, the only place I can see that
something like that would be desirable would be in for example
notifications where you should be able to manage your sitewide
notifications and hence might want the sitewide master rather than
the subsite master (and even there most of the time you probably
really want the subsite master template anyway). I would be more
inclined to add a context="path" to the master tag to have it
look up a different subsite's master template (so your example would
become <master context="/">).
If you can come up with some more concrete examples I am certainly
willing to entertain the idea that I am misguided here.
