stage 4 colon cancer with mets in the liver, 1 lung and the brain

I was diagnosed with stage 4 colon cancer in early May with liver, lung and brain mets. Early on I had Gamma Knife for the brain mets and it seems to have worked well. I originally had 9 spots in the brain. This week, I was told that 1 spot has done nothing...not growing, not shrinking. Dr says to watch it. The other two need to be treated either with Cyber Knife or whole brain radiation. The problem is that one of those is very close to the area of the brain that controls the left side of my face and he's afraid I MAY have some impairment sort of like Bell's Palsey on that side. Might not be able to close my left eye, have some slackness and weakness in that side of my face if they treat it again with Gamma, Cyber Knife. I have been told that whole brain radiation always causes short term memory loss and some calculatory function loss. I have to make a decision on which way to go SOON, so any information you can provide will be greatly appreciated. Anyone who has had experience with one or both? Thanks in advance.