Depending on how you look at it, the 6 shot revolver could be said to have an advantage.
Certainly, I am coming around to believe that in .357 caliber, the L-frame revolvers have an advantage because with just a little bit of good gunsmithing they can be either 6 or 7 shot. The cylinders interchange fairly well (sometimes perfectly) and with a little bit of work on the advancing hands -- it's best to have a few to work with -- a nicely pre-timed action can be set up for both a 6 and a 7 shot cylinder for the same revolver. Get the 7 shot cylinder moonclipped if it isn't already and you have and ideal "car" gun for Central Mexico.
For most of the Mexican Practical Shooting, revolver strings are limited to 6 shots. You can enter with a 7 or 8 shooter, but you better have some dummy cartridges or snap-caps in place of the extra round(s). That can make the fast reload slower as you try to make sure the correct round falls under the hammer so the next shot will go "bang". You CAN install a 6-shot N-frame cylinder into an 8-shooter and it will work with the action but it cannot be fired since the cylinder charge holes do not line up with the barrel. This because to make the N-frame cylinder an 8-shooter, the charge holes are a bit farther up than normal to give space for enough metal between the chamber walls and thus will not align with the barrel.
You CAN remove the barrel from a 627 and install a regular N-frame barrel and it will line up with the cylinder charge holes, but you need to adjust the extractor guard to work with the ball-bearing lockup as the regular "nose-pin" lockup into the front of the extractor rod will not work as the distance will be different due to the fact that the threaded barrel hole in the frame is at a different distance from the center of the cylinder due to the difference in distance of the 8-shot charge holes in the cylinder as opposed to the 6-shot charge holes in a regular N-frame cylinder. Confusing stuff, I know, but that's how it works.
This is a regular 6.5 inch Model 23 Barrel installed onto a 627. It works fine, but you need to modify the extractor guard to work with the ball-bearing front lockup. This was a Marine Custom shop gun (not mine). Always lots going on at the Custom Shop.
My normal Mexican PPC/NRA Action Target Class Revolver for Mexican matches was a Model 14-3 K-38 with a Model 14-5 Heavy Barrel that I bought off a Major U.S. parts supplier installed onto it. The innards were all from a Model 64 Stainless parts kit, and the Model 64 cylinder had been sent off to T-K Custom to be moonclipped prior to it "going South" as it were.
Although the front sight used the normal sight pin, I simply obtained a proper super-small pin-punch for the S&W sight pin and a selection of sights to use as the match-conditions dictated. (I believe your Rappy comes with the DX Interchangeable front sight system, so you won't have to pound out the pin all the time to change your sights.)
If there was a problem with the K-38, it would be it's lack of power. My "choice" competition revolver was incapable of penetrating car doors and delivering a Major Caliber impact, so it was excluded from consideration as an "all around revolver" that could be used for anything. Thus, I also had a selection of N-frame Magnums remarked to .38 Special -- as well as a 627 that was a close to an "around gun" as I found except it was an 8-shooter and presented irritations when it had to be used in 6-shot stages. We did have a small number of the original 7-shot Bauman cylinders for the N-frames, and these worked well. So you had the 7-shot Bauman moonclipped cylinder for Real Life Vehicle action, and the regular 6-shot cylinder for Club events.
A 6.5 inch Model 27 registered as a Model 23 that belongs to my best friend with a 7-shot Bauman cylinder installed.
The Bauman cylinders were made to be ONLY USED with moonclips. However....
...the Custom Shop guys modified them to work with loose cartridges. Brilliant.
The problem with the N-frame guns is that they are really big, with a longer trigger-reach than the K and L frame guns which are the same trigger-reach. I have thought about it a lot in the last week since you mentioned your Rappy and have come to the conclusion that when I return to Mexico I should covet a 686 with either a 5 or 6 inch barrel. If I get one with a 6 shot cylinder I will obtain a 7-rounder and have it moonclipped. If I miraculously end up with a 7-shooter, I will get myself a 6 shot cylinder and fit it to the gun. This way, my "competition" revolver can also double as my "to and from the range" revolver. The nice thing about the Rappy revolver -- or the S&W Performance Center 7-shot equivilent -- is that I believe them to come with the Interchangeable Front Sight system that I think is so desirable.
However, the Weigand Interchangeable Front Sight base can easily be installed onto a regular 686 barrel, and then you have it!
So, yeah. I'm thinking of going L-frame in the future. It eliminates the need to have so many different revolvers to do so many different things. (In Mexico, you are only allowed to have 10 guns registered. That sort of sucks, although it also leads to a lot of "cloning", where several different guns of the same caliber are kept in different locations but all have the same serial number. Again, really stupid rules and restrictions lead to really obvious evasions.) But still, with a 4-inch L-frame and a 6-inch L-frame you have your Service Class gun, your Target Class gun, and either can be used in a "Big Boy" match with 180+ Power factor loads if needed -- or in a Pin match -- and you still only have 2 revolvers that do it all. I had to have 5 revolvers to cover the same territory, all either K or N frames. When I go back, I'm starting from a pretty-much fresh slate and now think I'll just go with the L-frames and be done with it.