Supermike,
When you chose radiosurgery did you evaluate the different machine options? If so, I'm curious why you decided on Gamma Knife over Cyberknife. I'm assuming that you weren't comfortable with the fractionated approach to treatment, but even in comparing the two on a one dose protocol the CK is slightly more accurate and does not require the headframe. While the latter is certainly something that many folks who select GK go through successfully, it never appealed to me.
If you haven't looked at different machines, of the three facilities you listed, Barrow has both and does use CK for AN's , Pitt has both but does not typically use CK for AN's because of a financial relationship with the GK manufacturer ( they use CK for everything that GK can not do) and mayo does not have a CK.
Either machines will ultimately get the job done well, but there are some differences that might b worth consideration
Good luck
Mark