Here's another variation (one I use often and appreciate a lot):

    make update UPDATE_TARGET=bin-install

Incidentally, if I remember correctly, you wanted to build from source
whenever you didn't have a binary yourself?  If this is the case, put

    BINPKG_SITES=

in /etc/mk.conf, otherwise the build infrastructure will attempt to
download pkg binaries over the Internet whenever you don't have them.

Cheers,  --Dave

P.S.  Question about bin-install for the pkgsrc gurus:  this seems to
  be doing the just-in-time su before doing the build (when no binary
  pkg is found); but I expected it to do it after the build and
  before the install--should I send-pr or is it supposed to be this
  way?  Thanks.