Is there are reason besides capacity to prefer an automatic .45 to a revolver (e.g. S&W Night Guard)? 7+1 vs. 6 rounds doesn't seem like too big of an advantage for the auto, plus you don't have to worry about a misfeed or forgetting to hit the safety in a stressful situation with the revolver.
If you reload, and if you work the machine carelessly, you may experience misfires. But that's true of revolvers as well.
A few comments to address your post. Yes, there are a few reasons to prefer a semi over a revolver. Your points are indeed valid, but there are other points to consider as well:
One does need to worry about "misfeeds" if one has a good semi-auto.
Forgetting to hit the safety can indeed hamper someone, and has happened to *very* highly-trained individuals. Whenever you see a conversation about this subject, many persons will invariably say that training will overcome this possibility. But the truth is that one can *never* train to the adrenaline-filled severity level of an actual "real life" combat situation. IOW, no amount of training can ever fully prevent a person from possibly forgetting to hit the safety upon presentation. Since I know that I'm human and can possibly make a mistake in a very stressfull and life-threatening situation, I choose to use a semi-auto that does not have a safety. Therefore, I think the worry about not hitting the safety lever is a moot point.
Advantage of a semi are increased capacity, easier concealment, faster reloading, and easier concealment of extra rounds. Also, a jam can often be cleared in a matter of seconds (depending on what jammed in the first place). When revolvers jam, it takes a gunsmith to fix it.
All that being said, I will also say that a revolver is a very good choice for defense as well, some reasons of which are the things you already mentioned. For many, it will take less time to become proficient enough to defend themselves with one as compared to a semi-auto. Revolvers are also a bit more tolerant of less than ideal handling skills (no jams due to limpwristing), or level of cleanliness. This is not to say that it's ok to shoot one with poor training, or to leave one dirty....
A revolver makes for a great weapon. It all boils down to what you feel most at ease with. I go out with a wheel gun from time to time and would never feel under powered or not having enough rounds to get the job done. There are ways do load a revolver really fast and it's nothing to carry extra rounds in speed loaders or the like. I only have one revo that is small enough to carry. A S&W Mod 25-2 that went through some mods at Jovino's shop in NY. It's a 45 ACP weapon so moon clips are as must. It's nothing to keep an extra loaded clip or two in a picket. And I can dump it and reload it almost as fast as my semi autos. It just takes practice. Just like it does to change mags in an auto in a hurry.
It all boils down to what you are most at east with. Having three loaded 9mm mags will do you no good if you can't hit your target where you want to hit it. If that means using a revolver then great. A lot of bad guys have ended up on the wrong end of one and not been around to tell the tail. There is no best gun. Only best for you.