James ~
I can't imagine anyone wanting AN removal surgery if non-invasive radiation is a viable treatment (it wasn't for me) but then you have the worry that the tumor will regrow. As fellow moderator Steve noted, on smaller ANs, there simply is no definitive criteria for choosing radiation or surgery. Doctors will have their preferences and, yes, biases. However, in the final analysis, the decision is the AN patient's and he/she will have to live with any negative consequence that may occur. As for age being a factor in avoiding microsurgery, I was a healthy 63 at the time of my debulking surgery and, 90 days later, FSR. I came through the whole thing just fine. My age was never mentioned by my doctor as having any relevance to the procedures. My good health was mentioned.
The quandary you're in is something every AN patient who has a tumor much below 3 cm has to struggle with. No one wants to make a 'wrong' choice. Research and consult doctors but never allow a physician to 'bully' you into one or the other. As one who underwent the surgery, I can tell you it's a chore but hardly the worst thing I've ever endured, just one of the more serious. The radiation (FSR) was painless, boring and uneventful - but effective.
Consider this website and the forums as a resource. We're not doctors but our members have a wealth of practical experience to offer as well as their understanding and support. We're all eager to share our collective knowledge with you as you struggle with a treatment decision.
Jim