Sorry to hear about your barrel. How bad is the pitting? If it is minor you may be able to still shoot it. Have you tried to shoot it?
I have a SS Huntsman and prefer it over all my other muzzleloaders. I have had it for 2-1/2 years and always clean it after shooting, never had a single problem with rust. A stainless barrel is not actually easier to clean, but it may be easier to see where you need to clean. Stainless Steel barrels DO rust, I have seen some Knights that were pitted badly. You still have to clean them thoroughly, but you may have a little more time before the corrosion starts. I clean them the same day I shoot them because I like my rifles.