This idea has been kicked around for awhile. I know one person who has thier F1s. I think they are using a lav roo over bcms though, I think he was trying to get ahold of some pure blacks not sure if he did yet though.
I have a hen that is from a lav/split blk orp hen x bcm roo. She lays a way darker egg than an orp and could pass as a pure black bcm if you didn't know any better, except her eyes are a little dark but then I've seen bcm with darker eyes. I've been debating putting her back with a pure lav orp but I really wanted to go with the pure black marans not bcm. I have a pure black marans hen that I am using next and getting some silver blk birchens soon too.
I have a hen that is from a lav/split blk orp hen x bcm roo. She lays a way darker egg than an orp and could pass as a pure black bcm if you didn't know any better, except her eyes are a little dark but then I've seen bcm with darker eyes. I've been debating putting her back with a pure lav orp but I really wanted to go with the pure black marans not bcm. I have a pure black marans hen that I am using next and getting some silver blk birchens soon too.