Hi, I see you're from Colorado, much different than here (up north in Québec). Here, by law, we need dedicated winter tires since the last four years, but personnaly, I used winter tires since I began driving 30 years ago. I always used steel rims for them, and giving me the opportunity to change them when I wanted, this is way more cost effective.
Also having 2 sets of tires doesn't cost more than having just one set, you don't wear one while using the other.
Back then I was using studded tires, but since the last 10 years, I can say that the studdless ones are more effectives in all conditions. Well except when icy around freezing point, below that, studdless becomes more effective, studs don't have the same benifits when colder, they are the best only around freezing point. This is where I'm less sure about your conditions in Colorado and won't give you any advise, you must know better than me for your main road conditions.
Having said that, I have a set of 16' steel rim, and found a good deal at Costco on Blizzak DM-V1 for 475$ one week ago in 235/75R16.
I paid 1000$ for 4 Michelins Latitude X-Ice seven years ago, so paying 50% less in 2013 was a good surprise for me. The Michelin lasted me 7 winters (I don't have to drive much during the weeks to go to work, I drive mainly during the weekends to go to ski, but if the Blizzak last me at least 4 winters, I'll be happy.
In your case in between 255 (650 rotation per miles) and 245 ( 661 rotation per miles) is not a big deal. There is not much difference price Wise, so either one would be good.