The Ruger Scout is a bolt so I don't think it would be a variant of the M1A. It's a variant of the other Scout rifles like the Steyr and Savage. They're great brush guns since they're light, compact, and the forward-mounted rail makes target acquisition faster. It isn't meant for a high-power scope because of the longer eye relief but can be used with pretty much any CQB optic. The short barrel also makes a great suppressor host, and I think both the Savage and Ruger models are factory threaded.
I think they're neat. I would certainly own one if I needed a lightweight deer or hog gun for hunting within 500 yards.