Any advantage to getting the .357 and just using .38 +p instead of the .357?
All that you're going to do is add more weight to the gun (a LCR is specifically designed for light weight and easy concealability).
The short 2" barrel doesn't really allow the .357 magnum to reach its true capabilities.
Remember, the .357 magnum is a high pressure cartridge, and uses slower-burning propellant powders to get an optimal burn. The .38 Special is a low pressure cartridge, and uses faster burning powders to get an optimal burn. You lose more punch with the .357 magnum, when you chop off those two inches of barrel length.
In these cases, bullet design is more important than squeezing out every last bit of velocity. This is why I recommended the Speer Gold Dot short barrel-optimized loads in the .38 Special +P. It will do the job just fine, if you do your job of placing the shot. Ballistics for this round out of a short barrel are pretty impressive, and in all honesty, there wouldn't be much difference between using this vs. a full house .357 magnum load, in that short barrel.
While all .357 magnum revolvers can also shoot .38 Special loads, doing this on a consistent basis isn't an ideal thing, since you'll have lead buildup in the cylinder where the shorter rounds' tips are. This won't be much of a problem if all you're using are the .38 Specials, but once you try to put a .357 magnum cartridge in there, you may notice that it becomes more and more difficult to put the cartridge into the cylinder all the way.
Sometimes the lead buildup is so bad that it takes a long, dedicated scrubbing to get it out. Not fun at all.
If you're going to get a .357 magnum, I