Thanks guys for all the input. Your comments have made me think of a few new issues. On waterfowling- it would be nice to be able to use a sling in some situations so that would bode well for a semi-auto. On an O/U in a boat or blind- is it difficult to break open the gun if the blind is a tight fit? I was thinking symthetic black stock on a semi-auto.
So...... now I am thinking that the main benefit of the O/U would be at the range where you could put your hand over the shells to catch and save them.
If a semi-auto is used at a range- do you just leave the shells on the ground?