That's quite interesting, kuduae.

My "late" hunting buddy Brad had a Ruger OU in 28 bore. I shot a bit of trap with it and it really hammered the birds.
Another friend uses a Turkish OU in 28 bore for his grouse gun.
I really don't see much "use" for a combo though, imho, unless it was with perhaps a 6.5 of some sort usable for moose.