trying to decide which PDM software is the best fit

I currently work for a company that employs 6 designers in a single facility.  We make assemblies that contain fewer than 500 parts.  Most of which are common to almost every design while some are design specific.  We are trying to decide whether or not Enterprise PDM or Workgroup PDM would be more suitable for us.  We also have ERP software called "Visual" by INFOR which would like to interface with.  Which PDM software should we implement?

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