Well, I’m new to this group, but the pears I am experimenting with are all fireblight immune or highly resistant, and take to -40C and colder. They are of commercial quality or better according to reports. Only a few varieties have fruited so far for me, but here is a description of the better ones. I am in zone 3 and all have been fully hardy so far.
Bryansk Beauty…a red pear, large, 220 grams, stores two months, exceptional taste
Simply Maria…a new release, hardy to -40C, large, keeps two months, excellent quality
Nika (Nick)…a large pear with a beautiful red blush, keeps 3 months…hardy to -40C
Autumn Korshikova…Hardy to -42C, large, beautiful, very tasty
Marshal Zhukov…Bore a full crop after many days in winter down to -42C (about -45F). This is a very large pear, as good as southern commercial pears. Named after the old Minister of Defence in the old Soviet regime
Sverdlovchanka…In warm climates this is an exceptional summer pear. In zone 3 climates it is an excellent tasting fall pear.
Krasnobokaya…(means “red on the sunny side” in Russian. This has fruited for me and to me the taste is better than any supermarket pear. Photo attached. This pear survived -48.3C in Russia with significant damage, but it did survive and recover. Photo attached from September.