I have placed some patches for etcupdate at
ftp://ftp.netbsd.org/pub/NetBSD/misc/apb/etcupdate.20060211.{1,2,3}.diff.

Here's what they do.  I'd appreciate feedback here on current-users.

* Expand the "-s" flag as follows:

  -s {srcdir|tgzfile|tempdir}                  (default: /usr/src)
               Location of the source files used to populate the
               target directory.  This may be any of the following:
               * A directory that contains a NetBSD source tree;
               * A distribution set file such as "etc.tgz" or "xetc.tgz";
               * A temporary directory in which one or both of "etc.tgz"
                 and "xetc.tgz" have been extracted.

* Remove the "-b" flag.  It is replaced by the "-s tempdir"
  form of the "-s" flag.

* Change "-s srcdir" to refer to the top of the source tree (e.g.
  /usr/src) instead of the etc subdirectory.  (There is a backward
  compatible test to accept either form.)

* In the interactive phase, enhanced the "s" command to be able to
  invoke alternative diff commands, as follows:
 
  s  Show the differences between the currently installed and new files
  sd  Show the differences ... using "diff -u"
  sw  Show the differences ... using "wdiff -n -l"
  scommand Show the differences ... using the specified diff-like command

  (wdiff is from pkgsrc, so including "sw" might be controversial.)

--apb (Alan Barrett)