The real issue about newfs defaults, from my point of view, doesn't seem
to be whether or not they can be changed by editing disktab -- it's that the
compiled-in defaults aren't good at all as they now stand, among other reasons
because it's reasonably difficult to install a virgin 1.0 system using the
install disks and scripts thereupon and still get good UFS performance.  This
could be dealt with by either A) asking the user for lots of complicated 
information or B) revising the default values to be more in line with
reality -- the rotational optimization doesn't seem to be an optimization on
most modern disks, if not all, and maxcontig should be reasonably big so that
clustering works right.

Thor