Disclaimer: I know what a scout rifle is, but I haven't studied them.
For the purposes you're describing, I would suggest building or buying an ultralight AR. Throw in 2 or 3 magazines and you should have an approximately 10lbs or less package including 90 rounds of ammo.
Here's my reasoning. You're planning for an urban environment. That's the one place that the military doesn't really complain about 5.56. You're probably going to be engaging at relatively close distances, sub 100 yds. The likelihood of bigger crowds or at least multiple targets at close range is greater in an urban environment. A couple of quick shots and move. (How fast can you work a bolt?)
If you were planning for a rural or maybe even suburban environment, I would be more open to a bolt gun. In that case, you may be at a greater distance, you probably have more cover, and there are likely less large groups. In that environment, take the one precise shot and move.
Under most cases, I don't see a reason to engage a target at several hundred yards. If you see the threat that far out, do your best to avoid it. You mentioned not wanting to get pended down. If they aren't engaging you at several hundred yards, avoid. If they are, you may be penned already.
With that said, if you like and want a bolt gun, get one and train. Just my thoughts. I'm no expert nor claim to be.