Hi, Mark - and welcome. I can't add much to the many previous posts but as my fellow moderator Steve, stated, your doctor covered all the radiation myths extant. I won't bother disputing them because some internet research can show you that they're mostly baseless.
My neurosurgeon debulked my large AN and worked closely with a brilliant young radiation oncologist to 'map' my subsequent FSR (fractionated stereotactic radiosurgery) treatments. He had no hesitation about recommending radiation as a follow-up treatment to my surgery and he was dismissive regarding the myths about radiation, basically saying that he had never seen these things happen and that he wouldn't be recommending radiation for me if he had any reservations about it being potentially harmful. This seemed reasonable to me as my neurosurgeon had 30 years experience treating acoustic neuromas and was highly respected by all who knew his work. He was an adjunct professor of surgery at prestigious Yale University School of Medicine in New Haven, Connecticut, a top-ranked U.S. medical school.
I'm certainly not a doctor and cannot credibly recommend a specific procedure to you but I would have to concur with other posters who've suggested you consult more than one (probably biased) surgeon on the best treatment for your relatively small AN. Irradiation (GK) is well proven at this point and certainly worth your consideration. Doctors are knowledgeable but they are also fallible and subject to bias and closed-mindedness, as we all are at times. Treat their opinions with the respect they deserve but make your treatment decision based on your criteria and your instincts, remembering that the result of that decision, whether it's good or not-so-good - will be lived by you, not the doctor(s) or anyone else.
I look forward to reading more from you in the near future and I wish you success as you continue to seek answers to your questions and work toward a final treatment decision. Whatever your choice, we'll be here to support you, Mark, rest assured of that.
Jim