X2 I have heard of a lot people having aggressive/mean hatchery RIRs.  Not to say there aren't sweet ones, too though.  Heritage breeds have much better temperaments in general.
		
		
	 
I have not heard about heritage breeds.  I am assuming they are like Heirloom vegetables?  (Old lines, not hybrids?)
		
 
		
	 
	
		
	
	
		
		
			
	
		
	
	
		
		
			Well techincally only old-world breeds can be called "heritage" but when you buy any bird from a breeder you get longevity (8-10 years vs 5-6 for a hatchery), better temperament, better health than what hatchery birds have.  Hatchery birds have their place, they are fantastic layers and cheap, and you can get them sexed at day old.  But they are done laying in 2-3 years.
		
		
	 
Great.  I wish I had gotten on here and found all of this out before I ordered from a hatchery!!  What are the breeds with the best temperaments?  Once I get rid of my two RIRs I will have a Brahma, Americauna, Barred Rock, and a couple of Silkies.  What would be a good fit with them?  Should I stick with more of what I have or can I add new ones? (I have heard Wyandottes are good and calm...)
		
 
		
	 
There is actually a wonderful thread on Heritage Breeds under Breeds, Genetics and Showing.   The one originally started by Bob Blosl was made into a sticky note teaching thread to preserve the wealth of information Bob started.  He died late last year.  
Phase II is also called Heritage.   
By Bob's definition a Heritage breed has a 50 year or longer history and has been accepted by the American Poultry Association with a description in the Standard of Profection.   And often the original strains are hard to find and are being conserved.
Heritage breeders prefer to breed their flock to the standards set by the APA and often show their birds.  They look at dual purpose as part of the history which sustains a birds age in the production feature.
 Hatchery birds have been developed for a particular side of production...either as layers or meat birds instead of both.  Hens which are layers will burn out within a few years because they were designed to lay 5 -7 eggs a week.  She can only do that so long.  The cockerels in a layer breed may or may not make tasty meat. The hatchery Australorp is an example: a record of 364 eggs in one year.
Birds developed to be heavies are considered meat birds.  They may not be the best layers.  Your grocery store chicken is a meaty or heavy.
While the feathers may look the same on a hatchery vs Heritage breed, you can tell the difference between a heritage bred bird and a hatchery bred bird by their  type, carriage and frame.  
I have both hatchery Wyandotte (2 left) and also Heritage Wyandotte.  There is a huge difference in their size,  temperament, egg laying and meat quality.   I have Heritage Cochin also.  
That all being said, my layer flock has Australorp, Marans, Minorcas all purchased over the years from Atwoods from Ideal Hatchery. Diet and care contribute to the longevity of these egg producers.  a few of my girls are 5 and 6 years of age and because of age are only laying 2-3 eggs a week.  
My Cochin/Wyandotte cross birds are great mother birds, lay 5 eggs a week, and are nice dinner table birds.