I'm not so sure I agree with the answer given by Krieger barrels in the previous post. I just recently purchased a Savage 116FLSS and prior to taking it out I gave it a good cleaning as I do with each new rifle. It took a long time to get the patches to come out clean even after running some JB compound through it. I noted this on my warranty card in the comment section and got a call from Savage when they received the card.
The tech rep for Savage told me what I already knew. That stainless is harder to machine than a chrome moly barrel in that it is more difficult to finish with a smooth surface. The stainless tends to be rougher than the CM so there are more areas for fouling to adhere. With this in mind, I would say that breaking in a stainless barrel would take a little longer than breaking in a CM barrel. As for accuracy - I don't think there would be much difference after several hundred rounds. But you would probably need about 10 rifles of the same model in SS and CM to prove it one way or another. It would be interesting and fun to do.