Large bird does not always equal to eating alot. My BBS Orps are HUGE and they are not big eaters at all. My Speckled Sussex is a little round thing with short legs and she is a voracious eater! Her eggs are small and almost white and she is two years old now.
The BRs are good foragers. They do not eat an unreasonable amt of food. I still believe that you cannot beat a Barred Rock in any department, except maybe as a broody since the breed doesn't have that tendency, generally. My Buff Orps are good foragers as well, but two out of three have been broody.