BMc, I grow the green-skinned, pink-purple-flowered Hylocereus stenopterus. They are mostly self-incompatible however I do get a few fruits that are not of my own creation periodically. They skin does turn peach-colored when mature (about 2 months), however I have found that the fruit has a nice sweet flavor at 35-40 days. I have not had a H. megalanthus ripe at the same time to compare re which one is "sweeter".
Someone was asking about crossing the yellow-skinned H. megalanthus with a red fleshed variety. They had such a cross available in the markets on the Big Island (Hawaii) in May 2012. Orange-skin, pink-flesh. Nice tasting fruit.
William, 2 cuttings in a pot is not a problem. Most commercial operations put 3-4 cuttings per post. Of course, they have many more pots and they are usually connected together for stability. Keep in mind that a mature plant can weigh in the neighborhood of 100 kg.