Out of the box a S&W revolver will typically have a double action trigger with a weight between 11 and 12.5 lbs. IMO these heavy triggers are due to concerns about liability. The good news is that it is actually very easy to tune these triggers to 8.5 lbs. in double action and have 100% reliability with almost any ammunition you can find. If you want to limit your ammo selection to Federal, Speer, or Winchester you can tune the trigger down to 8 lbs. without any misfires.
BTW, my experience recently is that Remington UMC and Sellier & Beloit are the 2 commonly available ammunitions that require a bit more power. I've also seen reports that the Winchester Winclean and Speer Cleanfire have very recalcitrant primers due to the use of lead free primers. Considering the cost of either of these "no lead" ammunitions I really don't consider them as practical.
Bascially, what I am telling you is that you'll want to plan on eight tuning the trigger for yourself or having a gunsmith do it for you. Because no matter what you purchase if it's a NEW S&W you will find the double action trigger rather heavy.
As for handling characteristics between the K and L frames in a snubbie, I think that the only noticable difference will be that the L frame will run 1 to 3 ounces heavier. Basically, a 7 shot 686 will be VERY close in weight to an older model 66 snubbie. It's one advantage to the 7 shooters, that extra chamber in the cylinder does reduce the weight. Go with a 6 shot 686 and you may notice it's a touch heavier than a model 66. However, with a 32 ounce revolver it will take someone with VERY sensitive hands to feel a 2 or 3 ounce difference in weight. As for the grip frame, the K and L frames share identical grip frames in the round butt snubbies, so no difference at all in the grip.
