The Ancient communicator doesn't give you access to your hosts memories. Daniel and Vala didn't know anything about the people they were in until they read the names. In fact, it was only because Daniel knew how to read Ancient they figured that out, the device didn't provide a translation for Vala.
Well, muscle memory is probably a different matter. The body-swapper wouldn't be very useful if you were, say, tripping all over yourself since you were a short person who swapped into the body of a tall person.