Lucuma for a rootstock is better for more cloudy and moisture areas with cooler high temps. I am in Southern CA and have a lowland Lucuma in the ground doing well. The highland Lucuma does not perform as well from what I have been told. I also have a younger Ross Sapote that seems to be doing good too.
Canistel is a more sensitive to low temps then Lucuma, I am not sure where Ross sapote fits in this. However I have heard Canistel makes a good rootstock for areas where below 40F does not happen much at all. Lucuma can handle 25-28F with out it killing the tree, this would kill most Canistel trees.