Given what I know now I wouldn't attempt to breed. I also wouldn't keep more than one breed. The vast majority of the behaviour and health problems here on BYC are from people attempting to breed with no real knowledge of what the long term consequences will be. When your chicken is only living to 4 or 5 years old and is prone to reproductive disorders at an early age, that would indicate that there is a problem in the genetics somewhere. Bear in mind these are not technically battery breeds.Just to clarify Tribe 3 is made up of Bantams crossed with Marans? Or a group that includes bantams and some other Marans crosses? Really interested, as I quite like my Marans temperament and size, and have recently experimented crossing them with some Isbars, and LeghornxCrested cream legbar hens. I plan on having the Marans as an integral part of my breeding groups.
Many of the integration and aggression problems are I believe caused by various breeding programs.
When a couple of memebers of the chicken club here read some of the threads and articles on BYC they were appalled at the pick and mix buy from a bin in a farm store of hatchery approach to chicken management.
It's not at all unusual for people here to have chickens 11 and 12 years old.