I think that trying to find a new cultivar with desirable taste and alternative growing conditions in the native zone of a tree is a great endeavor. So if it tastes poorly, give it a yank. If it did morph into a flavorful new cultivar we all win. This is how "new" mango are discovered, no?
If a reasonably flavorful annona that could live north into zone 12 with the characteristics below were found, WOW! that's a tree lots of people would like to have!
From the UF:
Common Names: Pond Apple, Alligator Apple
Origin: Florida, the Bahamas, Caribbean, Central and South America, West Africa
U.S.D.A. Zone: 10A-12B (30°F Minimum)
Plant Type: Large shrub to medium-sized tree
Growth Rate: Moderate
Typical Dimensions: 30-40’ tall x 10-20’ wide
Leaf Persistence: Deciduous, semi-deciduous
Leaf Type: Simple
Flowering Months: Abundant in spring, but can be year-round
Light Requirements: Medium, high
Salt Tolerance: Moderate
Drought Tolerance: Medium
Soil Requirements: Wide
Nutritional Requirements: Low
Environmental Concerns: Low