Michael OShay has provided some excellent information but one should take into account that parts of Alaska consistently has warmer weather than West Virginia (my state), many states directly south of us and all the states to our north. Additionally, chickens that lay double-yolkers over a protracted period are prone to serious reproduction problems and loss. Many if not most LF breeds begin their POL by laying a few doubles but that stops after a short while.
@RhodyRed , One would think you already have RIRs. If you don't find them to be satisfactory in your conditions, I doubt any of the sex-links will impress you.
I've never had any health issues with my Black Sex Links although I've run into a few of those issues with my Red Sex Links in the past. For whatever reason, the Blacks seem to be hardier (perhaps it's the Barred Rock hens used in their breeding). In fact the oldest hen to ever lay eggs is a Black Sex Link (marketed in the UK as Black Rocks). http://www.dailymail.co.uk/news/art...ritain-squeezes-eggs-THIRTEEN-years-last.html