I agree Julie. I also have a very unusual surname (only 5 in UK), and I worry about been tracked, but as already said, my concern is not so much the GSCC registration as the general availibility of information on the internet.
I am very careful about my information and where I put it, but as a mother of 2 teens I know they are not quite so vigilant, especially where using our surname is concerned (as they cannot see any reason not to include it on facebook etc).
It is a worry I am sure all front line professionals have had, and unfortunately, it is usually a worry that comes with the job.