Just wondering what differences other than the tube diameter.
You are right, the 30mm tube diameter and more internal adjustment is the main difference between the PROSTAFF 7 and 5. The 5 comes in a lot more configurations including First Focal Plane, Illuminated Reticle and Custom Turret options.
Right now there is a Nikon Sponsored Promo for $100 off the PROSTAFF 7 4-16 Nikoplex scope. Under $400 now!
I hope this info answers your question?