I can help you with my experience and my brothers. We were both diagnosed with a AN and each had different treatments with different results.
My brother had Gamma Knife in 2010. It resulted in a loss of hearing in his affected ear. Totally deaf in one ear. He also had some bouts with Veritgo and still has tinitus. I believe he chose Gamma Knife because that was the procedure his Doctor used. With Gamma Knife he had the HALO bolted to his head!
I had Fractionated Sterotactic Radiation (FSR) in December 2010. I had five treatments. Once a day for 5 consecutive days. I felt tired and sluggish after my treatments. But it is like getting an MRI with your head bolted to a table. What they did for me was they molded a face mask, like a hockey mask, and the mask is bolted to the table. As a result of the treatment my hearing did not diminish at all. I still have tinitius but I still have the same level of hearing from before my treatment. The Tumor has stopped growing and is considered dead. I still have MRIs every two years as a precaution.
Why is this? Well the Gamma Knife is one large does of radiation and it tends to hit the target tumor but there is always some collateral damage to surrounding healthy tissue. The healthy tissue is the auditory nerve so as a result you have some or total hearing loss. With FSR you get 5 smaller doses. If some healthy tissue is accidentally targeted there is sufficient time between doses for the tissue to recover. And with the smaller does there is a lower probability of exposing health tissue to the radiation.
I researched this over and over again before I decided on FSR. The other thing is that not all Doctors do all the treatments. I went to a AN specialist at UPenn and he only did Gamma Knife. I found an Oncologist near my home, on the Jersey shore, who did FSR and things have worked out so far. I also believe that you do not need a AN specialist to Zap your tumor. An Oncologist zaps all kinds of tumors every day. Find a relatively young one who still loves his work and you should be in good hands.
Feel free to ask me any questions you may have. For background, I noticed ringing in my ear and had an MRI and discovered a 1mm tumor in 2003. Very very very small. I had an MRI every year and it would grow 1mm a year. After 7 years it was time to do something because it just kept growing.