Current research suggests that a homogeneous group gets better results because similar people will yield a more focused result. You can have several different homogeneous focus groups, each with different demographic characteristics.

What shouldn't focus groups do?

Focus groups work well in tandem with a quantitative study (see #1 on the list above), but shouldn't be used in place of a quantitative study when there is a lot at stake. If you need to generalize results to a large population or statistical data is required.

What are homogeneous groups in research?

an aggregate of individuals or other elements that are similar to one another in a number of significant respects. In a social context, for example, a homogeneous group might include members who are the same age or have the same socioeconomic background, values, work experience, education, and so on.