[Phil Masters]

Most of the time, you'll send what you've got. SAIs are expensive, and ghosts generally have the right to choose what jobs they take, so you won't always have an unlimited choice. SAIs can in principle be trained with unlimited skills, and have built-in bullet time reactions (though ghosts could have those modeled in), so logically there could well be an SAI that's better at any and every job -- but that doesn't mean one will always be available.

Also, a ghost could have specific experience of archaic or unusual technologies, particular people, or whatever. And ghosts are based on human brains, which can have (in game terms) a wild range of IQ levels and peculiar Talents; finding a ghost with the same capabilities could be difficult or expensive.

Also, if you're sending your infomorph into a situation where it may have to enter into legally binding contracts, you want to send one with the greatest possible legal rights in that location. Property can't usually enter into contracts.