I'm in zone 9a. Malabar Spinach is not a great survivor. My plants did not return from cold and they hardly make it a year in the warm. They are very susceptible to disease and lack of water. My well established plants died in the summer without irrigation.
In the spring my plants grew at rapid pace and produced abundant food. In the fall they are pathetic. They are decent to grow as an annual. I prefer Basella alba (green) to Basella rubra (red). A great way to grow them is to use a hogwire cage and train them in a spiral around the cage as they grow.
The Perennial Vegetables book says they are perennials here... I disagree.
I recommend Chaya, Edible Hibiscus, Moringa and Katuk and many others as perennials for this region.