The bees I run go to CA for almond pollination. When I first started with bees it was recommended to me to use Carniolans for overwintering. The more time I spend with the bees the more I like the Italians. They hold larger populations and produce more honey for me. The last few years we have been having wet spells and the carniolans keep shutting down on me(not all of them). Three years in a row now it has been the Italians that do the best for the way our WI honeyflows are.
I just reread your post-I haven't noticed a difference with 1 strain of cells doing better than the other in terms of mating percentage. I've gotten Italians(Homer Parks, Parks/Wooten, and Aurea), Carniolan, Carniolan/VSH, and Ontario Buckfast cells shipped to me from Miksa over the last few years.