It has been my experience that a pancake style holster holds the firearm closer to the body, tilts less, and is less top heavy than most paddle holsters. The only advantage a paddle holster has is that it is quicker and easier to put on and remove.
From what I've seen, paddle holsters tend to be among the least concealable belt holsters. In addition to stansdds's points, the butt of the gun tends to stick out. But it may work if you wear a heavy jacket and never take it off or bend over. I'm not a fan of paddle holsters, but I do like the version by Kramer Handgun Leather because it includes a snap loop that wraps around the belt for extra security.
There are pancake holsters that use snap loops that wrap around the belt so you get the benefit of the pancake holster holding the gun close to the body with easy-on/easy-off capability. While I don't have experience specifically with this type of holster, I have experience with holsters by Side Guard Holsters and TT Gunleather, and they both offer snap loop pancake holsters. They make excellent quality gear.
With a gun like a 686, a good gun belt is important if you don't already have one. I like double-layer leather belts, and they're often available with additional reinforcement. I prefer Beltman belts, but there are plenty of good makers. Nylon belts, like the Wilderness Tactical Instructor belt with reinforcement, are good, too, and less expensive.
I mention this in pretty much every revolver holster thread, but I would recommend looking for a holster that carries the cylinder even with the belt. You can see that by comparing the relationship between the cylinder molding and the belt attachments. It tends to make the most stable arrangement, which helps with both comfort and concealment.
Hope that helps.
