Just passing along an answer I received from Sage on how EES users will determine if they become concurrent or named CRM users:
Question: How and when will current MAS 90/200 EES users elect whether they will be become concurrent or named based CRM users with 4.5?
Answer: MAS 90 User Based customers will be able to choose at the time of order if they want concurrent or named users. That will determine how we place the order. If the customer is existing User Based, the CRM users they currently own default to concurrent unless they specify otherwise.