I'm going to go against the grain a little bit here and say "it depends".
If you are shooting a tight-patterning load (like many of the reduced recoil buckshot loads currently on the market), you shotgun is going to shoot very much like a rifle at indoor ranges. Most folks prefer some sort of sights on a rifle.
At a shotgun class last year, I found myself dropping targets during a close range drill that I'd had no problem hitting a little further out earlier in the day. This was because the same 'coarse sight picture/mount' that got pellets into the target with the larger pattern wasn't sufficient to get hits when the pattern hadn't yet opened up. I was frustrated until I slowed down and got the sight picture I needed to see at that close range.
The obvious response to this is: "So, you're off by a little bit. Who cares - it's a shotgun!". Again, I might go against the grain here and say "it depends".
Doc Gunn does an excellent segment on bullet placement in his Tactical Treatment of Gunshot Wounds program that is worth the price of admission by itself. One point he makes is that when we're shooting in self defense, we're not targeting 'the bad guy'. We're targeting
very specific structures within the bad guy. In the same way that a hunter does not target 'the deer', but rather, very specific structures within the deer. These structures, in both cases, happen to be pretty small.
So, what I'm getting around to here is that, if you're working to get what amounts to a single projectile into a fairly small area on a big target, you might find rifle sights beneficial.
I, too, really like the speed of beads. The compromise I've found is the XS Standard Dot express sights. The big golf ball front sight and wide, shallow rear are about as quick as a bead for me, but still give me something to allign and make a precise shot if it's needed up close or further out (with slugs).