I agree, they are generally the same size, I think the burundi and kigoma types can "appear" larger because of exceptionally large nuchal humps compared to the gibberosa species such as mpimbwe or moba types. In general frontosa are rather slow growing but over time achieve larger than average size in adult hood. I consider a 12 inch cichlid to be quite large, frontosa commonly exceed that (both male and females) but it takes more years to get that big than some similar new world cichlids such as oscars etc...