Thanks all.

Bill, true, very true. But then what would all of you do with your
extra time when you're not helping me? ;-)

I didn't ask about the straps because I assumed if the new buckle
didn't work with the old straps, then they must be a different width
and won't fit through the sleave on the tongue of the shoe. While the
buckle just attaches with a single screw, the strap slides through a
sleeve on the tongue that is not changeable (sic?).

It'll be a bummer if instead of replacing $30 of hardware I end up
spending much more on a replacement. These shoes have served me well
for over a decade. The bottoms are well worn and there's a small hole
in the upper on the one side (crit crash circa 2000), but they still
do the job. :-(

I'll contact Sidi to confirm and report back on what I hear.

Dan