I have had success with cold-hardy and super-cold-hardy avocados in my yard over the past few years. The cold-hardy ones I have include Mexicola, Brogdon, Day, Bacon, and Winter Mexican. The three Day trees and the Winter Mexican I grafted myself. The Day trees are some of the fastest growing trees I have ever planted. Thankfully the Days have slowed down in growth otherwise I'd have to prune them. Two of the three Days suffered slight leaf burn from last week's freezes but their emerging blossoms are fine. The third Day in located closer to the lake I live on and is frost-protected a bit by a Live Oak tree and a Southerm Maple tree overhead. I have two Mexicolas out in the open on the north (and coldest) part of my property - no cold damage whatsover to the leaves and emerging blossoms. The Brodgon is young (though I had a 25' Brogdon in the 1990's) and the Bacon (with blossoms) were both unaffected by this latest cold snap as well. The super-cold-hardy species I have were unaffected as well and these are also located on the north side of my yard: Joey (another graft of mine), Brazos Belle, and Fantastic.
Several winters ago, I had a major freeze (<23 degrees F) which destroyed the flowers on the cold-hardy varieties but the super-cold-hardy species were unaffected including their flowers amazingly.