I shall try to answer Kim's questions, although I am not entirely sure
that the topic "SACD Questions" belongs to this list, being somewhat
technical in nature.

I do not have any experience with the SACD format, and the classical
performances offered in the DVD-Audio format are not many, and those in
the SACD format, are even less.

I have acquired two Audio-DVD discs, the Handel's "Messiah" with the
Mormon Tabernacle Choir and Vivaldi's "Concertos and Chamber Music"
with Musica Alta Ripa.  Both were played on Pioneer's DVD Player, which
supports both formats, and on a more than average 2-channel stereo system
(including headphones), and the sound was very good, IMHO better than
one obtained from a similar high class CD counterpart.  It is said that
the sound would be even better, using a 5.1 surround system.

I allow myself to quote from Amazon.com:

   "Equipment Needed
   First off, DVD-Audios will not play on normal CD players.
   You'll need a DVD-Audio player in order to fully capture the
   capabilities of these discs.  A receiver with 5.1 analog
   inputs and five speakers (left, center, right, left surround,
   right surround, and a subwoofer) should also be used to capture
   the surround-sound capabilities of DVD-As.  While pure DVD-As
   will not play on standard DVD players, most releases (including
   all the titles produced by Warner, Atlantic, and Elektra)
   contain a Dolby Digital surround-sound mix, making them
   playable on any DVD player.  Though these discs are primarily
   audio-only, you'll be best off using them in conjunction with
   your TV, so you can watch the additional onscreen features
   (see below) and navigate the menus with ease.  It's all a
   little complicated, but music-loving home theater enthusiasts
   won't be disappointed!

   Improved Sound
   Thanks to a higher sampling rate than that of both standard
   DVDs and CDs, DVD-As have an incredibly detailed sound.  And,
   when played through a proper home-theater setup with five or
   six channels (speakers), you'll get to hear your favorite
   music in a whole new light--in surround sound.  Depending on
   the remastering, the effect of surround sound on your favorite
   album can be subtle or dramatic, but generally speaking, every
   DVD-Audio sounds better than its standard CD counterpart.  "

Zeev Schor