Guns, Dogs and Blades QnA

Waterfowl hunters: please educate me on your preferences for "non-toxic" shot shells. Looks like I'm going to have to buy some for upland wing shooting in my new state. So I like using my under/over for grouse and pheasant and have always run an extra full choke over a skeet choke. Lower barrel for those close ups and the top for reaching out and sealing the deal if I miss the first shot. I think that I hear folks say not to run steel in restrictive chokes. Also I have a 28 gauge side by side that is tough to score kills with and is limited to 2 3/4". What do ya'll think about Tungsten vs bismuth for heavier hitting power in smaller shotguns? The Tungsten folks are claiming I can kill stuff with No.7. Man I'd have a hard time buying that, at the price of Tungsten, if it doesn't deliver. Please advise and thanks in advance.
So the results are in, keep in mind my references are all duck hunting guides here in Arkansas. To a man and one woman the vote was unanimous, Tungsten for the win. Hope this helps.