Voted 590 for my needs.
To something posted earlier:
Heat Shields, aka Barrel Shrouds, in California fall under the list of "Qualifications for an Assault Weapon." So they're less common here because, believe it or not, put enough fun things on your shotgun and it becomes an assault weapon. You either get 2 or 3 things off the list, which includes barrel shrouds, pistol grips, bayonet lugs, folding stocks, etc.
Also, the barrel shroud isn't an option for the 590 when you select ghost ring sights, though I'm not entirely sure why. Perhaps the mounting interferes with the sighting or something.