I think that we should not confuse "rusticity", generally defined by the resistance to the important cold, and "productivity" in this or that climate, being a fruit.
That the tree does not die is a good thing, but generally we expect fruits! And there is not necessarily won for varieties a little exotic in climates that are not.
I am not a specialist in trees, but I do not think that the "cold" experienced in winter has a great influence on productivity, except:
a) the tree dies, its trunk bursts, etc ... (the olive trees in many regions during the winter 53, for example)
b) frosts at the flowering / fruiting stage ... (this 21 April, for example)
So a tree that will "survive" the cold weather (the ones we cross once every 10 or 20 years) will generally produce ...
Or, if it does not produce, there may be, in the case of exotic plants, other factors: cross pollination necessary but impossible for lack of a sidekick in the corner, absence of a specific pollinator, photoperiod ( influence of the length of the day / night) ...