Well, mine is an SRA683, and on the frame it says Dahon Dove D8. So it is not a C6 with an upgraded cluster. I did find a site in Hong Kong advertising them, all in Chinese of course, but Google translate was able to make some sense of the text. I was going to put the link in but I am not allowed to yet. But Google should find it for you, if you search on "Dahon Dove SRA683" As you will see from the pics they apparently come in three colours.
With the wife having a 20 inch bike, it is interesting to be able to compare them. For riding, larger wheels are of course better, especially on bumpy surfaces, but for folding up into a small space the smaller wheels are great. Since we bought them with the plan to take them world travelling with us, the smaller wheels on the Dove are best for us, and I would trade in the 20 inch for another Dove if we could. Or a Brompton for that matter, but they are much more expensive. We got the Eco C7 for NZ$250, the Dove for NZ$500, while the two used Bromptons I saw for sale here recently were at NZ$1200 and NZ$1500. New they are around NZ$2000, depending of course on the level of equipment. There is a Brompton dealer in this country, but none for Dahon. I think someone is importing the Terns too. But folding bikes are not something you see in the ordinary bike shops here...unlike Tokyo, where among all the full size bikes at Bic Camera, we saw a wall with about a dozen different Dahon models on it. None like mine though, with the small wheels and multi gears, or I might have splashed out and bought another one.
John