a couple of thoughts. while it's true that a 24/48 signal would get truncated to 16/48 by a DAT deck, it's really not too bad. certainly not ideal, but it still is a pretty good option.
of course, another alternative would be to just run the V3 for the show instead of the portico. analog out of the V3 to your 744, and digital out to his DAT deck. while the V3 won't give you the same sound as the portico, its certainly no slouch of a pre-amp either.