Is the much advantage in shooting 3 inch slugs or turkey loads over the 2 3/4 loads ? I have shot the 3 1/2 don't care to ever again ! So I am not even considering them .
I can tell you from personal experience that accuracy suffers with using 3" slugs, due to the increased recoil. I tried a box of them ONCE. As far as 3" in a shot load, you will get increased recoil as well, but you will have a pay off in increased distance and shot weight. If you turkey/goose hunt they are worth a look.
I use only 2 3/4 inch slugs and 3 inch turkey loads and waterfowl loads. I agree with FDX about 2 3/4 inch slugs being more accurate but I think its more than just the recoil. I think 2 3/4 inch slugs shoot better out of a 3 inch chamber than a 3 inch slug.