Nice to meet you, someone after my own heart, I am trying some Pioneer Chickens from McMurray also know as Dixie Rainbows this year. My understanding is they breed naturally and lay 300 large eggs a year, 5lb+ dress out weight at 15 weeks. I also have some F2 generation eggs in the incubator, the lady I got them from says second generation comes in 4.5lb+ in 15 weeks. So we will see if this can turn into a truly dual purpose sustainable breed.
Those sound like really interesting chickens, I'll be interested to hear how they treat you. I ended up with 8 Mottled Javas this spring, and I'm excited with everything I'm reading about them. It may be a breed I try to hang on to, very dual-purpose and I think they get pretty large as well.