mossberg 590 9 matte blue (nor blued version) vs mossberg 590 9 shot mariner?

So ive decided to make the next gun a mossberg 590 instead of the remington 887 tactical. Now i already own a mossberg 500 for hd, but will prolly give that to the gf as her designated gun incase of breakin and to use at the range (its got a 18.5" barrel on it but im just looking to find one with a longer mag and to have both of us have a hd gun)

The reason why im asking this is because i have relatives in florida that i like to shoot woth when i visit and since they live on the gulf ive been considering going for the 600 dollar mariner version because of how much salt water use itll get down there (which is quite a bit as we sometimes do over the beach typ stuff) so if i cpuld have any opionions, facts, or experiences shared by u all thatd be great, cause if the matt blue 590 9 shot sp is just as good as the mariner version when it comes to saltwater and freshwater corrosion resistance ill just skip the mariner