The Browning BPS is my FAVORITE pump waterfowl gun, but I own a Mossberg 500 for that. I like the mossy's lack of a loading gate in the magazine, the tang safety (Remingtons are crossbolt and I shoot lefty), and the price. It's not as smooth a pump gun as an 870, but ain't far off it. The Browning is wonderful, but the cost puts me off. I ain't takin' no expensive gun in the salt marsh ever again. I learned my lesson beating up a beautiful double over the years.
I thought I wanted a 3.5" gun, too, a while back when I had a good goose lease. Then, I discovered Federal Tungsten Iron which works BETTER than lead and brings geese out of the stratosphere light lightening. Yeah, it's a little expensive at 13 bucks for ten rounds, but I don't hunt geese all that often. After using that stuff, I'll never use steel on big, high flying birds again. It works fine on ducks over decoys, use it for that, but all my goose hunting is with Federal Tungsten Iron now days. It's 7 bucks cheaper than Remington heavy shot and while the Remington stuff is probably good, I can't see it working any better than the Federals. The problem with steel is it just don't hold its velocity due to lack of density. Yeah, you can stuff a 3.5" full of Ts, but it's pretty expensive, too, and closes the gap on the 3" Tungsten Iron in cost while it STILL doesn't work as good. Nope, I'm a T-I convert, don't need no stinkin' ultimag.
One thing, I have only hunted turkey once in my life. That might be a good use for the 3.5" gun. I'd rather have a 10 gauge, though.