Mike,
I have no direct knowledge of stainless steel barrels, I don't own any. John Krieger is my barrel maker of choice, he has made the last three I have purchased, including a M70 Featherweight. That is probably where I got the idea. I spent quite a bit of time talking with him at an NRA convention in Texas a few years ago. Here is what he says (bottom of page):

http://www.kriegerbarrels.com/RapidCat/c...;CompanyId=1246

It is noteworthy that Lilja disagrees:

http://www.riflebarrels.com/faq_lilj...ls.htm#subzero

However, other qualified people think stainless and cold weather is an issue, here are some threads:

http://yarchive.net/gun/barrel/barrel_steel.html

https://24hourcampfire.com/ubbthreads/ubbthreads.php/topics/3142153/1

For me, this is just another one of those safety margin things.