I have worked with Datafrond and the PLM In A Box solution. It has been a great fit for our company.
PLM-In-A-Box does an excellent job of addressing the complexities of PLM and is built around the traits of the WIndchill architecture that you can only learn from experience.
They have put together a solid package that is flexible and well designed. Do yourself a favor, speak with a reference. Don't be afraid to ask the hard questions.