I haven't had barred rocks but someone I know in black canyon city (almost as hot as Phoenix) says they do well for her in the heat. the blue birds in your package, that lay light brown eggs, will have barred and blue plymouth rock as the foundation. Seems there is a tradeoff between doing/laying well in summer vs laying thru the winter but I think if you end up with a mix of the rainbow you should do well. I'd proceed with your package and hope for the best neighbor-wise, I really don't think you could get quieter birds that'd tolerate the heat. As for the longevity of the sex links, sure these are all "egg laying machines" in some sense, but I'd guess a lot of people who buy these high-production birds, also supplement light through the winter, because they want so many eggs, and the extra light burns out the birds at least as much as their genetics. Not that they all do, but maybe enough to skew the results.