On-the-Other hand, if you can afford to buy ammo for a .45, or if you get into reloading (recommended), then I don't see any particular advantage to a small bullet hole compared to a large bullet hole.
9mm is cheaper to reload than .45ACP, and signifigantly cheaper than factory ammo (and can be made better, as well, if you are up to the task!) if you buy the components in BULK quantities.
Since nearly nobody reloads 9mm, brass is laying on the ground nearly everywhere, too. The same can not be said of .45ACP.