Upgrading from NW04 SP16 portal to NW04s portal

We are in the process of planning a project the will require a 3 party vendor to access our NW04 portal sp16. We are looking for any advice on doing this. We are considering upgrading to the NW04s portal. This would allow us to use the multi tenant functionality. We would like to hear from someone that has done this similar type of project. We are looking to avoid any pitfalls.

Rock