I took the root-sucker in June and know the "new" plant is still growing....I think you can do it more o less always, if dormant you'll have to wait to see the result, but I think it's possible.

Very interesting 

It's easy to propagate...you can take one of the branch growing from the roots, take also part of roots and plant in a Pot....with this you'll get your result for sure.

If better than P. edulis I wonder why it's not commercialized ?!

It seems Pouteria lacuma.....it's a fruit native of highlands of Perù, it's a very dry fruits what an atipic flavor...it's often used to make drink mixed with milk..i really like it and also the plant is pretty beautifull

Yes, in Sicily the temperature is never too high during winter.....temperature above 65F are very rare. As said by Pancrazio this could be the reason why those mangos survived during that event.
It would be interesting understand if there is a sort of acclimatization also for Mango...may be what we know is imperfect and other mechanisms have be understood....I think it's not impossible to have more cold-hardy mangos..


P.s.

Just for fun....are there some related specie that could be hybrided with Mango as it happened for citrus with P.trifoliata?

I don't know....but is the plant sane? how are the leaves?

All your efforts have been reward  .....without the Florence June's storm you would have more fruits....interestingly you got the fruit from first flowering and not for second even if you had much more flowers of the second.
Should it be better to let the "April" flowers? How do you explain the fact that you lost all fruits of the second flowering while the only fruit from first flowering is ripen?

Anyway congrats....let's hope your experiment will last for many years

Pollination troubles?

As for the Avocados why could not be possible also for Mango to find cold-hardy cultivars? With the selection something could happen or may be still exist but have to be discovered (Cultivars of North India, near to Hymalaya or something else)

Maybe grafting Lemon on P.trifogliata could help you....but Lemon is one of the most sensitive to the frost.

Just for curiosity , how long do Mangos produce fruits in Florida...I mean, from the early cultivars to the latest one ? Are there cultivars that flower two times for year?