Hey Nancy, I seriously debated between GK and CK. My own conclusion, after researching accuracy, tumor control, side-effects. etc., was that the two are essentially the same, unless you have hearing that you want to preserve, in which case, CK is better. Both are very accurate machines (though there is sharp disagreement among the two camps as to which machine is more accurate than the other). And I don't think there's enough info out there to suggest side effects are any different in GK v. CK. GK advocates will tell you to go with GK's longer track record, which I think is a fairly important consideration. But since CK has already been in use since 2000 or so, and since Stanford has been using fractionated treatments since the early 90s, with tumor control rates around 98% (and control rates of around 99% with CK) -- I think it is a very safe bet that CK achieves the same tumor control rates as GK. Bottom line: Both work well. CK gives you a better shot at hearing preservation. CK also doesn't require the head frame, but since that is just a temporary inconvenience, I don't think it should determine which treatment you select.
At least that is what I concluded. I go through my whole research/decision making process in my website, which is below, if you are interested.
Be well,
Francesco