Re: For whom the mat calls..
I certainly haven't done a study of any quality, but have made some really general observations concerning the people I know who practice aikido.
Most are male Caucasians.
Most are college-educated.
Most are employed in white collar occupations.
A fairly large number are involved in IT work of some sort.
Many are also musicians, at least at the hobby level.
Many are artists who paint or sculpt in a variety of media.
Many seem to surf, dive, swim and sail (unique to location?)
Quite a few are educators.
Virtually all I've met have been really nice people.
With the exception of the water sports, these observations have been fairly universal in my travels around the country.