Personally, I am a huge fan of GRAMPS. I've used it for years, primarily because it allows me to use it as the repository for all of my genealogy research, but frankly I have never tried sharing amongst my family in this way. I have found getting good quality info from family members can be tough, plus there are always conflicts to resolve. (No Aunt Bertha married Uncle Gorgonzola in 1954, not 1957). Issues related to conflict resolution make version control and the ability to "go back in time" and check the history of specific edits are critical for me. Gramps is version control aware.
I'm not sure how the gramps UI handles native chinese characters, but it has mature multi-language support. There is an active translators page, which covers the UI and documentation - the chinese (zh_cn) is in a partial state of completion.
Maybe I'm just paranoid, but I would be cautious about managing my family tree online if it was going to include information about living people. Uploading a GEDCOM to rootsweb is one thing, but when you start managing information about peoples kids, you need to consider very carefully the security of the site you're uploading the data to.
I find it easier to be the official 'collector of family history' interview & gather & publish family memories often. I have distributed copies of GRAMPS with the DVD's I produce, but no one (in may family at least) has installed it and contributed anything. Family member do call with info or send me email, but as people soon find out, maintaing accurate family records is actually a lot of work!
But hey! maybe I descend from a long line of slackers. YMMV ;-)