Border Collies

She is fine with other BCs or runs away from terriers if its any other breed, there will be a response.

Whats amazing her Zip is that she has an on/off switch. It doesn't take much get her jacked up. In fact, it doesn't take her much to get over the top. Most BCs needs to be played with or jacked up prior to the ring, you can't do that with Zip. Once she sees the ring, the switch is on. She goes at 120%. She gets her tug after she is done. Since they will be trying out for the World Team this year, they're working on controlling her over the top behavior.

Now Zach, he is softer and more loving. He still doesn't know he isn't a puppy because he likes to jump into your arms. He is working on his first year in agility. BTW, my instructor got bored and decided to enter 3 of dogs in rally and obedience since the BCs were injured.

Breeding that is too focused on trial success can produce a variety of not-so-useful characteristics in dogs.  Generalizations are impossible because it depends on the style of handler, and the type of trials they prefer.  The problems you mention aren't really an issue because the judges don't reward style or judge the dogs - it's all based on what the sheep do.  So not matter what, a dog that lacks courage will not show well on sheep that are tough, and a dog with a hair trigger will do badly on nervy lambs that bring that out in a dog.  You see enough trials and you'll see the major failings in most any dog.

But we did have a period, for instance, when it was fashionable to have a dog that worked a certain way that required a lot of fine tuning, because the top handlers were winning with those dogs.  But, it was a type of dog that didn't translate well to your average farmer who needed a dog that could work naturally right out of the box. 

Now those handlers are starting to face some dissatisfaction even with their students and are finding it hard to establish lines.  So they are swinging the other way, looking for dogs that are more natural and self starters. 

Before that trend, we had a ton of major trials where a certain kind of really crazy, deerlike sheep were used exclusively and the dogs that won had a lot of eye and were very careful workers.  That was fine, but when too many like that are bred, eye starts multipying because it's progressive - when you breed eye to eye it increases in the next generation.  We need the more upright workers, too.  Soon we started seeing well-bred dogs who could barely move sheep, though they certainly were easy to get started.

It's a pendulum.  But the checks and balances appear even at that level too - the trials are balanced by the people who are using the dogs, and the people who are using the dogs keep the breed consistent by going back to the trial standard. 

Once she sees the ring, the switch is on. She goes at 120%. She gets her tug after she is done. Since they will be trying out for the World Team this year, they're working on controlling her over the top behavior.

This is the difficulty, in reality.  The balance I talk about with regard to work ethic, doesn't mean a dog that can relax away from the working context.  I'm talking about a dog that is thinking and acting with reference to the whole working package - listening, feeling out pressure, calculating probabilities and developing plans of action, accessing memory on previous circumstances that were similar.  All this while the instincts are screaming YEE-HAW!

This weekend a friend had an agility bred dog out at a lesson day.  Not all agility dogs fall short on working ability - there was another there from the famous Kuykendall Bill/Kate breeding and she was quite nice.  But this one was a good example of what I mean. 

When you breed for agility you have no idea where the package is starting to fall apart.  This girl had sheep and had gotten this dog pretty much for that purpose.  One of the parents had an instinct certification of some sort - woo hoo. 

This dog wanted to circle, circle, circle but if she managed to stop the aimless circling (and the chewing on sheep that went on inbetween), the dog would wander off - he was plenty interested, but at the point when a correctly bred Border Collie's instincts would say, "YES!  That feels RIGHT!  Do it AGAIN!"  he lacked that internal input and the game was no longer fun.

So poor old Star (not his real name) will be sidelined and she's looking for another dog with proven instincts.