For the last year I've been breeding a Naked Neck rooster with the following hens: English Orpington; Naked Neck, Rock, Slow White Broiler and Red Ranger. My primary goal was meat production, with a secondary goal of egg production. It's been an interesting experiment.
On balance, the most consistently large offspring were from the Red Ranger hen, followed by the Slow White Broiler. I was surprised at just how consistently large those chicks where. I got dressed weights of between 4 and 5 lbs from the cockerels at 13-14 weeks, and similar weights from the hens at 6 to 8 months. The other crosses yielded decent, but much smaller sizes. However the hens proved to be consistently superior egg layers. It ended up being a good balance for me -- the broiler offspring went to the freezer and a few of the Rock and Orpington offspring are being kept for their eggs.
I was also pleasantly surprised at just how hardy those two broiler hens have been. They both laid well throughout their first laying season and made it through multiple, 100+ degree summer days (albeit it camped out under misters). They haven't started laying yet this year, so I don't know what type of decline in egg quality/quantity I might see in their second year.
I had initial plans to breed a true dual purpose heritage flock, and I still might some day. However, crossing a slower growing broiler hen with my Naked Neck has proven so easy and productive, I'm sticking with that for now.
Two things I learned that bear keeping in mind:
--Depending on how many meat chickens you want from your flock, you either need to butcher some of pullets; or raise twice as many birds as you need and plan on selling a lot of pullets. Otherwise you will soon be overrun with hens. We chose to butcher excess pullets. That proved much harder to do on a emotional level than it was to butcher the cockerels. However, they really did make for excellent eating.
--If you want to breedfor certain qualities, you need to have the space and temperament to be evaluating and replacing roosters on a regular basis. This is what ultimately caused me some pause in my breeding efforts. Having a mature rooster that I trusted and the hens get along with, is such a nice thing. Even though my Roo isn't as large as I would like, he has proven to be such a good and easy boy, I was reluctant to make a change, and go through the turmoil of a raising an unproven, randy cockerel in my flock to replace him.