If you're a student or teacher of Chinese, we want to hear your opinion on whether you prefer to have simplified and traditional characters together in the same practice book so that you can compare both forms, or separated into different books so that you can focus on just one. Please take our poll and let us know what you think!
traditional of simplified
My answer would be that it depends on whether the book is meant as study materials or reference materials. Reference materials, even for beginners, definitely should have both forms. For study materials, I would prefer that only one form was highlighted. For example, in a reading book for beginners, I would want simplified or only traditional. In a writing book for beginners, I would want one form as focus, the other form provided simply for reference.
Once students are beyond the intermediate level, I would expect that they should be getting used to reading (not writing) both forms of characters, so alternating both forms in one book might be valuable (i.e. lesson 1 is in simplified, lesson 2 in traditional), with vocabulary and index containing both forms. This not something I have seen at this point. Such a design would possibly narrow the marketability of the book, but it would force students to work on reading both forms, rather than just reading the one they are used to. For advanced students, I think being able to read both forms is a reality that they will have to contend with eventually.