There's quite a bit of taste test information at
Taste Results and the 2007 results are also contained in this UC publication:
http://cesandiego.ucdavis.edu/files/63550.pdf.
The 2006 pitaya festival was covered in the January/February 2007 CRFG Fruit Gardener in an article written by Emory Walton, a friend of Edgar Valdivia. There's not really any mention about taste results in that article. Interestingly, the writer indicated his favorite pitaya is H. peruviana but Edgar hadn't brought any to the tasting that year.