RE: Red dot scopes for slug hunting..
I hunt the deer woods with a slug gun bearing a Tasco Pro Point 5 red dot. I love it.
I have not gotten anything with it yet, but it is SO easy to acquire and track a target with both eyes open using a red dot.
It's as fast as using iron sights, but you don't have to align rear and front, just point the dot. SWEET !!!
One of the things I like best about it is that, in addition to a brightness control, you can change the dot size.
For dim settings and longer shots, use a low intensity small dot, and for really bright areas, make the dot larger so it's easy to see. Check your sight picture periodically during the day as the lighting changes. My sight has 11 brightness settings, but I kept it at 3 or below (and on the smallest dot) for a whole day last year adn ti was fine, but again -I hunt the woods where it's a bit dimmer than a field.
I always put a fresh battery in for a day of hunting, and carry a spare. Used batteries are for the range only.
I leave the sight on all day so I don't have to mess with the dials to turn it on for a shot.
Some of the red dot scopes I've shot have a parallax problem, so make sure the red dot is in the middle of the FOV before shooting, or experiment at the range to see if the error is considerable on your setup.
Good luck.