Mona:
I regret that I cannot offer you any specific advice on treatments or facility as I had surgery followed by FSR, which is somewhat different than GammaKnife or CyberKnife, alone. I will suggest that you not agonize too much over your choice of treatment as your time to decide is, by your choice, not indefinite and the stress of choosing a specific treatment (GK or CK) is, as you know, quite stressful. Generally, as you noted, the success rates are fairly similar for both radiation procedures you're considering and well into the 90th percentile, which is excellent. Frankly, you can't get any guarantees on outcome and seeking them is futile, as you know. I would 'go with your gut' (first instinct) and choose the procedure you feel most comfortable with and not seek 'perfection', which will likely prove a futile search. I wish you the best and will pray that you make a wise decision. I only wish I could do even more.
Jim