I picked up the 870 tactical with ghost ring at cabelas last year for $550 plus $50 rebate. They do occasionally go on sale there. I've only used mine for plinking at the range with slugs and a few skeet sessions so I haven't really stress tested it. A couple of comments up make me want to locktite in the rail and sights now though lol. The bright orange PLASTIC magazine follower is a really stupid decision on remingtons part. Seriously, how much money does it save and it looks like an airsoft gun with it. I also wipe it down with an oily rag for the reason mentioned above too.
I would never in a million years pay $700 for it, but $600 or less no problem. I am not very handy, so I like to buy firearms with rails and stuff already attached, so I don't mind over paying a little if it save me work. I've never use a 590, other than the location of the safety, and dual extractors on it (i think) nothing really sets them apart in my mind.
On a side note, have you considered the Winchester SXP Defender or Ultimate defender? I just picked up a field and camp bundle, they are all the same gun essentially, but man, what a super slick action and sort of a blowback assist effect that if you get the hang of, can do some serious rapid fire without coming off target much. It's made in Turkey which is why they are a couple hundred bucks less. I can't find the Ultimate Defender anywhere in stock online, but if I do, I'll definitely get that variant as well.