I understand your point...from a defense situation. I do like a DISPLAY of what appear to be a combination of both prey and defense for that vary reason.
My issue however with the concept is that we are left to read the behavior of the dog, as we can't read their mind. Generally speaking, fear based response to conflict will show greater signs of stress AS the dog APPROACHES its threshold for avoidance. Avoidance however is not something I want on the table; therefore, I select for intensity WITHOUT signs of avoidance. Now, with that said, the dog is selected to maintain intensity without showing the signs of fear.
From this, one could argue that we are therefore producing a more confident fear fighter due to the higher intensity and greater determination to remain in the battle...OR...one could also argue that instead of creating a more confident fear motivator...perhaps instead we are simply creating a more INTENSE prey motivated predator...and that is when we find the most confidence as a hunter generally doesn't fear their prey...but just kills it. So...
1. Perhaps we are creating a BOLDER but already intense dog...(a braver fearful dog)...are we [u]adding boldness to intensity[/u]?
2. Perhaps we are creating a more INTENSE but already bold predator (a non-fearful dog)...are we [u]adding intensity to boldness[/u]?
In other words...are we adding A to B or B to A? To answer that, I would like to remind us what we are starting with. What is our genetic base...prey or predator? The dog is both. Now the question becomes, which type does a given breeder prefer?
With that said, I would like to mention that while if dealing with GREAT DOGS of either type...the two end products appear the same...but the motive is different...and upon close inspection a trained eye is more likely to see signs of such motivation as the duration and intensity of a battle is increased. The greater both components are in the dogs (intensity and boldness), the more difficult it becomes to decipher which of the two is the primary component of motivation and which is the supplemental motivation. Some may argue, does it really matter? Well, what we need from the dog is action...not theory. So, in the end, the proof is in the pudding...and once again artificial selection provides for that need.
Endorphines for pain and adrenaline for power are not only products of fear. Sex produces such. Athletes are able to tap into such. I have tapped into such before without ever experiencing fear. Marathon runners get a 2nd wind after "hitting the wall." These are products of endorphines and adrenaline.
If you think one can't be intense without fear, well...I would like to remind you blood hounds have tracked unto their death. In other words, some animals don't just fight to the death. Some have worked themselves to a "point of no (natural) return" and yet still continued to work until they themselves extinguished. It is rare...but artificial selection allows us to capture such genes as it allows us to use UN-natural means (artificial interference by man) to save such awesome specimens...so once they are identified they can be treated for their "no-return" display and via medicine...indeed return and contribute to future generations of such working stock.