It's more than that - the bass bar on modern instruments is substantially heavier, because string tension with modern wire wound strings is higher than baroque

It's more than that - the bass bar on modern instruments is substantially heavier, because string tension with modern wire wound strings is higher than baroque era gut strings; the older instruments are more lightly built. The tone you get with gut strings is completely different than with modern strings - more complex, more resonances, but a modern style instrument will deaden that somewhat, you really want a period instrument to take advantage of gut strings. https://www.youtube.com/watch?v=7y4lcQ7BTLw https://www.youtube.com/watch?v=7y4lcQ7BTLw The neck is also different, but that affects reaching the high end of the fingerboard more than accoustics.