All of the technical issues have already been addressed, so I have nothing to add there. Beyond that, the preference between L vs. N for a .357 is a very subjective one. I love this discussion and find it interesting - we've had it before and if often re-occurs. I find the .357 to be the most widely versatile cartridge extant, and having a number of guns in it makes sense. I currently own:

3 K frame .357s (2 2.5" and a 4")
2 L frame .357s (a 2.5" and a 4")
1 N frame .357 (a 3.5", also had a 4" until recently)

One of my favorite games is to shoot different guns head to head with identical loads, .38 up to heavy .357.

The full lug and more compact design of the L give it a decided recoil advantage over either a K or an N. My 4" L with smooth targets weighs identical (41 ozs) to the 4" N frame with Magnas. The lug, and more compact frame make the L decidedly handier with heavy loads, but it is not a massive margin. Both make controlling magnums MUCH easier than the K frame. People criticize the lug for making the L harder to point, but I don't shoot skeet with mine. I have a Shotgun for that. I try to put multiple rounds into a single target to practice neutralizing a threat, and that is where the 686 excels in handling. The action on my 1st generation 686 (the 4") is also among the finest and smoothest I've ever encountered.

In the woods, I will carry the 3.5" N or the 4" L based on my mood or a whim - I love them both quite a lot. But I do agree with those above who say the N feels good in the hand, with a Tyler and Magnas, it feels great. I put plain targets on the L to get a good feel, but it's less pleasant feeling than the N (though the recoil control and distribution is better).

For CC, I will use one of the 2.5" K's, however. The compactness, decent controllability, and power make it a truly superb CC gun.