"-I know the moon clip makes reloading very fast."
why worry about reloading? Just make your 5 or 6 shots count.
Another main advantage the .38 has is the ability to use any bullet design it wants- revolvers are not picky about feeding different bullets. This allows the revolver to shoot bullets with a deep, wide hollow point that would never feed in an automatic. Try loading a 158gr lead hollow point, with that huge hollow cavity in a 9mm casing. Then, IF you got it to load and feed, try pushing it to 900fps or so out of a 3" barrel. There is a reason that the FBI used a S&W model 13 3" for many years, loaded with a .38special +P lead hollow point. That combo was, and still is, an awesome duo for personal protection.
Also, the 9mm is faster out of a short barrel due to the extremely high pressures. If you are gonna shoot a 9mm in a little pistol why not use a .357? I'd think that 9mm would tear a little J-Frame apart as fast as 125gr. .357 magnums would. Auto pistols tend to stand up to high pressure rounds a bit better than a small or medium frame revolver (say a glock 19 vs. an S&W K-frame)
If you want a 9mm, get an autopistol, and if you want a revolver get it in .38, .357, or .44