Conventional wisdom suggests UHF is not suitable for item-level tagging: The tag is too big, UHF won't work on liquids, metals, or small items packed in close proximity to one another, and UHF has too great a range--all of which ignore the fact UHF Gen 2 can exploit the near field just as easily and much more effectively than HF. That means anything that can be read by an HF system can also be read by a UHF system, including items high in liquid or metallic content.
This article provides information to help you make informed choices on tags and technology.