Hershel,
I can see my fellow colleagues have a similar viewpoint to mine; we won't even install a NuPoint on a 5000 as it offers no real benefits. That being said I know some customers are set in their ways and the product states that it works with Mitel products, but I would be contacting them and finding out what type(s) of integration (Analog, SIP, OAI) they provide and support, and what the customers equipment is setup for before going forward. In the end you can most likely be able to match or emulate the features they are using now.
Thanks,
TE