Once in a while I get tempted to try the red one [?carnosa?] but as I live in an apt, and doubt they would survive outdoors at my folks' place overwinter, I just admire the flowers and move on.
Just bought a passion flower for my mom this year. She had one one summer that grew so rapidly that I would have sworn if I weren't looking it would have started reaching for me if I stood for any length of time near it. She even got a passion fruit out of it!
Paul - I have seen the red at the Botanical Gardens and was amazed by it .. very bright and unusual from the common purple/blues. I saw an orange one at a local nursery also.