Joining the discussion late and not sure who wrote:
I should also mention that I
like the "6-pack" panel page on the Garmins as a potential backup in
the event of vacuum pump or electrical failure, and wonder how much
difference the faster refresh rate on the 496 makes for this page. I
guess I am leaning toward a Garmin at this point, but would first like
to hear some other comments on these issues.

In regard only to the comment above about the 6-pack instrument page, I
have a tandem airplane with two Garmin 296's (one in front, one in
back). Since there are no instruments in back, that 6-pack instrument
page not only serves as the dual backup you mentioned above, it also
gives the back-seat pilot/passenger access to info he/she can't see on
the panel itself over the shoulders of the front-seat pilot/passenger.
These little hand-helds are worth their weight in gold, IMO.