I was never a vest guy, probably because I love crawling all over the place... And while shotgun shell belts are cheap and they work, I never liked 'em.
I always preferred stock class harnesses, and you can pick up a decent Ronin Gear harness for like $20.
Now as for 2 pistols? Not my thing, I wouldn't do it. Much easier to run, gun, and reload one pistol than it is to deal with 2. If I did however... I might use a holster (or two holsters) rather than some kind of sling.
Quit now . . . it's embarrassing to get eliminated by a pumpgun!