I still have not exactly figured out if gamma knife and sterotactic are the same thing or not but my wife (49) had sterotactic in October/05. The procedure was involved some slight discomfort with the halo that they put on but she said it was far better than it looked. Other than the halo the procedure is completely painless.
She had whole brain radiation in September too. Her tumour has shrunk from 2.2 cm to 0.6 to 0.8 cm as of a couple of weeks ago and it continues to shrink. Is it worth it? Unquestionably yes !!
Good luck and best wishes to you.