If I were in your (Baka-Tsuki's) position, I'd say go for just one version. You guys should focus on getting a good translation out. I came to you guys because I figured Baka-Tsuki would be a place with lots of interested people and experienced translators. I was looking for a place to discuss the text and learn things from other people, and you guys could get a translation in return, so it seemed win-win both ways. Certainly you guys should decide on the format of the other chapters independent of whatever I may do right now for the Prologue and Chapter 1. In fact, I'd get him take over my translations if he wishes, if he is as you describe him, he's far more skilled in Chinese than I am in Japanese. I can't comment on the differences between the Chinese and Japanese versions, but I imagine you guys have dealt with this kind of thing from previous translation projects. If he does the first novel entirely by himself, the style may be more consistent.
Note though that the Prologue has
many subtleties, you may wish to check with him if/how they're reflected in the Chinese version.
For my part, I don't mind someone else taking over. I'll still be working on the Japanese version, right now I've been discussing it with people in other forums as well, not just on the wiki here only. I don't know if anyone else (Shapeshifter) has attachment to this project though.
