His Coffee plus Cocoa farm is close to Borai, in Trat province, close to the Cambodian border. His coffee is Robustan so no "altitude/temp" problems with that. As I say his Cocoa is a new crop, 1st year in farm so the plants are maybe 24 months old, so no growth or yield data is yet available. Having said that if you look at the requirements for both it's basically a Tropical environment required.
Visually, to the non expert farmer, the young Cocoa trees are growing at the same rate and just as healthy looking as the young coffee trees planted at the same time.
I am not sure where he intends to sell the Cocoa, I will investigate further.