Just a quick comment. In the same way there are many more 3D artists than there are Level designers, there are many more level designers than there are systems designers.
I'm working on a title at Sony at present and we have been trying to recruit decent systems designers for nigh on 9 months now with little success. Virtually every designer's CV that comes through is LD. Almost no-one classifies themselves as systems and has experience to back it up. If you can get some skills and experience in this role you are rare as rocking horse sh*t and not likely to have any problems finding a job.