Because of the more controlled processes in a structured focus group, greater within-group variety can be managed. A structured focus group also allows more variation in numbers of participants. You may be able to create a climate where differences are explored with interest rather than confrontation. If so, even greater variety may be useful. If well facilitated, diverse panels can offer a number of potential advantages.
More diversity means more differences of opinion.
In turn, that can allow deeper interpretation. But of course this requires more skilled facilitation. For this reason I try to make contact with each participant just before the session begins. To this end, I often ask participants to arrive a little before the planned start. Coffee, fruit juice and biscuits are available.