I can't speak for the load data of 9mm out of a revolver, since most statistics I've seen are for pistol barrel (no cylinder gap). However, you get FBI standard penetration out of modern (and some non-modern) 9mm hollow points... It's pretty much assumed by most reasonable people that 9mm is adequate for self-defense. It's almost the same with regards to penetration when compared with similar offerings (same companies, same bullet-type) in .40 S&W and .45 ACP:
https://www.youtube.com/watch?v=c8gm7ZTkDxc
The above video is "tnoutdoors9," while though he is not a ballistics expert, he does some really good, fairly scientific tests. You can watch scores of them, and .40 S&W, .45 ACP, and 9mm are all pretty similar when you get down to it. This makes sense, because when you compare the ft/lbs of energy between the major offerings of these calibers, they are all around the 300-400 ft/lbs mark. Yes, you can find more ft/lbs in .40 and .45 ACP than 9mm, but really those are the exceptions to the rule of production calibers...
So, I don't believe you are really going to see much of a difference between .38 SPL and 9mm, at least not one that would concern you in a gunfight or at the range. If you feel you NEED to shoot .38 SPL, go ahead and pay more money to do so. I'll stick with 9mm and be happier and better trained for it.
People have been saying that the 9mm kicks more than .38. Well, that probably is not an issue as the 9mm gun weighs more.
As far as 9mm accuracy is concerned... my 986 is probably one of the most accurate pistols I've ever shot, caliber aside. There is no reason why 9mm can't be accurate out of a revolver, but really? That's not going to matter in a sub-nosed revolver, any caliber you are spitting out of it.
And moon clips? Moon clips of 9mm are the easiest, fastest reload you will ever get out of a revolver short of .45 ACP in moon clips. You'd have the best chance under stress conditions loading a fixed clip than anything else.
