Our decision between a 550 and 560 hinged on many of the comments featured already. However it seems like most went 560 and we went 550

Disclaimer—we fall into the category of never seeing either model in person. So fingers crossed! We leave in 15 days to pick her up!
Obviously the couch / bunk beds are very cool. We have two dogs and no children but hopefully children down the road. We discussed it from a potential planning point but figured our kids will be like us and while they're small, they'll fit fine in the 550 and when they get too big, it'll probably coincide with when they'll be wanting to tent camp outside from us anyway. Kids, right?
We really loved the traditional styling of the 550 and its compact nature. We tent camp when we can but also just love to travel and as dog lovers know this can prove tricky on friendly hotels, the hotel proximity to featured point of interest, and associated costs. Leaving said dogs—not open for discussion.
Due to our passions and acitivies, we count on being outside more often than not. While the extra space of the 560 does bode really well for a rainy day—it still just wasn't enough argument for us specifically.
We recently began field trials/hunt tests for our dogs (more travel and long weekends) and love to duck and bird hunt. Waterfowl and even true wild migratory birds in South Carolina can be minimal to maintain through a whole season; travel is preferred. Enter again costs and ability to find more than a sketchy duck shack to stay in while still staying in remote locations and our 550 should really fill this gap for us nicely. We'll be doing a good bit more general ol' US of A sightseeing/state/national park touring but my hope is we'll be able to head out to some new states and areas for some beautiful family hunts and time afield doing what we love.
Dinner bell after sunset!