As a guy, and a Dom; age does factor in, but only in that I have a range I can be okay with. 10 years older was my first sub, and have dated a sub that was 11 years younger. Age wasn't really a factor as much as intellect and compatibility.
Though I do find if you meet someone in the 18 to 23 stage, they lack a mature personality that comes with the age of an older woman.