I find it funny how when the issue of the Non-NFA "AOW-like" shotguns is brought up, people say "You're gonna trust that thing to be considered legal just based on the opinion of the ATF that they can change at any time?" Which by the way is highly unlikely considering that it's not just the ATF's opinion, it's the law. And has been like this since the 60's (so I heard, no proof on that date). If the ATF wanted to change it, I'm sure they would have done so the first time someone tried to build that gun.
While with the sporting exemption in a case like this, people are perfectly willing to trust the legality of their gun just based on the ATF saying "Meh, sure why not. We'll exempt it. But just because you asked nicely" In this case it is purely the ATF's opinion since they have complete discretion in deciding wether your gun is sporting or not.