With glass and mount it will weigh 10 lbs, or close to it. I'd carry that much if it offered any real advantage, but a 10 lb rifle with a stubby 16" barrel is just dead weight. You can carry a 6 lb rifle with a full length, far more accurate barrel and be much better off. But if the SR762 were the only option, I'd use it before I'd stay at home.
I own several rifles, never given any thought to having one setup specifically as a back-up, but usually take 2 when traveling any distance to hunt. Stuff happens.
I rarely use a spare tire either, but keep one.