The customer numbering sequence - which becomes the Customer ID in GP...could just be sequential numbering?
The analysis could be handled through the customer class ID and the user defined fields.
It would be a lot easier to just code a sequential number for customer ID. So each time a new customer adds themselves - you increase the last number by one - then auto generate the class ID based on location, business sector, customer type etc. This way you can use the class ID to roll down common values during integration [I presume you are using eConnect?] - and you can analyse / report based on the class ID.
Ian.