No experience to report on with this configuration, but in regard to the last observation, here in RI such a firearm is specifically banned by hunting regulations for use during Muzzleloader Deer season... I would guess to make it easier for Conservation Officers (I think they call them 'Environmental Police' now, sheesh!) to tell at a distance if someone is sneaking a shotgun into the muzzleloader season.
That shows the outdated ignorance of governmental lawmaking in regard to firearms, since anyone who would opt for a shotgun in preference to even a traditional front loader of sufficient caliber and thorough design is actually placing a ballistic handicap on himself, not cheating an advantage. Of course with a pump gun he would have the option of multiple shots (which someone like this would probably need! :-D )
What a world! :?