RE: Slug Gun Scope?
I use a Bushnell Elite 3X9X40.
I know that's not the best scope money can buy, but I think it's a good scope. It's fogproof, and around here the weather changes a lot and we hunt in the rain a lot so that's handy.
I always keep it turned down to 3 so I can get an accurate shot off in the woods or in lower light situations.
A red dot scope IMO is great for fast target aquisition.
BUT, again, IMO your slug gun with the right sabots, is very capable of taking a whitetail at 200 Yards, and I personally want (or need) some magnification at that distance to make a good ethic shot.
Good Luck,