I'm late to this thread, but here's my experience with my heeler, for what it is worth.
I got my pick out of a litter of 13. I did a personality test on them at 5 weeks, and based upon that, I picked my dog. As with any breed, the temperament varies. Mine is at the outside end of the spectrum.
I picked the one that was the boldest, most inquisitive, feistiest, and who seemed to be the brightest. That meant, of course, that he would be the most challenging, but for me, also the best. He has required some careful handling, as he has extreme alpha tendencies. He is alpha to our 105 pound German Shepherd, although the heeler weighs in at about 48 to 50 pounds.
This dog is an excellent watch dog AND an excellent guard dog. He is only 2 years old. So far, he has done a lot of obedience work. Now that he is fully mature, I have begun doing some agility training with him, just for fun. He is a good herding dog, and has learned very quickly what is expected of him. He will bring in the goat herd (we had some issues with a temporary fence and had problems with escapees for a time). He shows all of the traits needed for Schutzhund competition and so this coming fall and winter I will begin his training in that area. This will hone and sharpen his guard dog work for our homestead.
He has a strong prey drive. He rids the property of rabbits. Because of his strong prey drive, I had to be sure he learned not to go after baby chicks, but he has good obedience training and the lesson on leaving chicks alone went quickly and was retained well. He is extremely bright and learns fast.
With such a dog, you do not want to inadvertently reward the wrong behavior.
He is extremely affectionate and loyal to his family. He is extremely stand-offish to anyone he does not know. Indeed, while he is socialized to accept strangers when we are out and about, if a stranger comes to our home, he will stop them until I tell him it is OK - no one comes here unannounced.
Also, he checks out any problem if the goats sound off. He will not tolerate stray dogs on his property. He is protective of me, the livestock, and his property. He is very possessive of all things that are "his."
He is VERY high energy, and he needs to work. He would not do well in any setting where he did not have work to do.
So, he is a GREAT dog for me. That being said, there were a number of puppies from the litter of 13 that were returned to the breeder. The people who got the puppies discovered they could not handle them. The breeder had to re-home them with owners who could handle them. Heelers are not a dog for everyone. They take someone who is dog savvy and who is willing to put in the time and effort to train the dog. But if you have the ability to handle one, you will possibly have an outstanding all-around dog for the homestead.
