FWIW, I'm in a similar position and own a Sam and it's an amazing bike: I live in Chicago, most of my miles are commuting, limestone paths, streets and roads. I have a Hillborne and it is dreamy for all that, plus loaded rides on paved/good condition gravel roads. I'd describe the ride as super comfortable, stable, agile, responsive but not at all twitchy. From what you describe you do and aspire to do, it seems pretty ideal. It's really a wonderful bike that's so versatile.
Having converted a vintage Rockhopper to be rivish in the past, there is just no comparison to the Sam. The Sam is so much livelier, more comfortable, beautiful, stable, and fun. That Rockhopper was a lot of fun and inexpensive, but to me, they are totally different rides.
Re chainstays: They're long by standards of most contemporary bikes, just not quite as long as an Atlantis or some other Rivs. Some folks on the list find that relative shortness to be an advantage, as it makes the bike more maneuverable both on an off trail. If you find yourself lifting your bike up stairs, onto trains, into elevators, you might appreciate the shorter wheelbase, too. I know I've been in some situations where I thought: good gravy this is a big bike (57 Sam from 2021); thank goodness I don't have one of the longer models!
All that said, I'm lusty for an Appaloosa, because I'm planning on some long distance dirt touring where I want big chunky tires, and a different setup than my Sam. But if that wasn't in the works, I wouldn't feel the need for any other bike.