i just did this BR roo x RIR hen earlier this year. i also had a new hampshire, columbian rock hens in there too and a couple black sex linked hens...ALL the chicks were black with white tummies and white spots on the head. there was no sex linking-need the barred rock to be a HEN for that to be a sex linked cross. so all the chicks looked the same, black, white tummies and white spots of various sizes on the heads.
they are adults now, just laying the last couple of weeks, beautiful large and extra large brown eggs. and they are BIG birds, good dual purpose birds. we processed the cockerals at 16 weeks, and there was a respectable amount of meat. the hens are all happily laying. some of the hens are barred completely like purebred barred rock, while most are laced or irregularly barred, or almost blue in colour with barring. quite a bit of variety all things considered, but they are all various shades of black/grey/blue and white/grey.