I have a RIR roo and a Banty hen. The hen is older, the roo is only about 4 months old. The hen went super broody and won't budge, unless you actually grab her...after getting pecked to death. She's very defensive and won't move for anything. She's sitting on 10 eggs. We candled them the other day, but can't really tell much...don't really know exactly what to see at 2 weeks, even after looking up images. Guess we'll wait to see what pops out, if anything. But we're wondering if the 2 different breeds and sizes would actually mate and what might be the outcome?
From what I've read it is possible for sandards and bantams to cross and the resulting offspring are usually in between the two parents, size-wise. I have a RIR oops-roo (ordered a pullet) in with lots of other standard size girls and a few bantams. He is so ginormous in comparison, I can't imagine him trying to mount any of them. He was hatched April 15th and I haven't seen him doing any rooster duties yet.... Good luck with your eggs! Hopefully by this time next week you'll have some cute little fuzzies!
Purposfully breeding Large fowl and bantams is NOT a good idea in ANY way. It would be very easy for a LF rooster to kill a bantam hen during mating, even though he may not ever mean to.
I ended up with some bantam standard cross chickens once. They were decent layers. Laid an acceptable sized egg, too.