Only issue with 17" wheels is potentially not clearing the brakes. Will have to get a design that has appropriate clearance for the barrel and spokes.
Apex makes 17" wheels that do clear original brakes on the Z4M. Their designs, which some consider a little derivate, have an OEM-like feel. They're also a forum sponsor and have a fitment guide:
https://support.apexraceparts.com/hc...-Fitment-Guide
I personally plan to get 18" Apex wheels for my car some day, but haven't settled on a setup yet.