I´ve been using Zoo since it´s first release. And since then it´s been a non stop of releases. The support is great and is the most poweful and easily customizable CCK I´ve ever known. Of course, if you need something special for the site you´re building, you´ll have to work a bit but the good news are you can do almost anything you need. About multilingual sites, it´s not supported by yootheme team but I can confirm it works with ZOO. Not out of the box, of course. In sum, it´s really recommended.