i always find that third party sites that sell seeds from other breeders tend to put different info for the strength an yield as to wot the breeders put on their sites
if your seeds are from greenhouse then the yields they state are possilbe but you need to grow the way they do using say 12k hps/room lighting an growing plants to their full size generally veging for 4 weeks
so it depends on how you want to grow if you got the space to grow them fully then yea you could get 600 grams easy but most people tend to get between 1-3 oz from each plant
there are grow dvds you can watch either on youtube or the greenhouse seeds website for both these strains im growing the white rhino at the mo aswell