danpaw wrote:That L frame is quite a bit fatter and heavier than a K.
Not really. Here is a K-frame and L-frame side by side. Most of the extra weight is in a little extra beefiness around the forcing cone (and of course the full underlug vs. half underlug). But weight-wise and carryability, there is not a huge difference.
L-frame 681 on left (steel version of 581 you are considering) and K-frame 66-2 on right (steel version of 19)
The L-frame is heavy, but you can definitely carry it. I prefer a high-rise Galco fletch holster:
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Above pic shows full target grips, which are not good for carry (but great for photos!). Try magna grips with a Tyler-T grip (as shown in my carry photo). You'll also need to invest in a top-quality gun belt. Mine is a horsehide belt from TheBeltMan - worth every penny.
From the guns you've listed, I would definitely go with the 581. Not only is that just a great gun, but you want no sights on a carry weapon you might have to draw.