Are you saying field trialers use e-collars to create drive/intensity or that it is a personal preference?
To clarify, because I musn't have been clear enough:
There are "tools" that in different sports are widely acceptable, despite some of the words used here. Not saying one person is right or wrong, but it's the truth.
The majority of people working in SchH and ring sports use prongs.
The majority of field trialers use e-collars.
Not saying that those tools are the BEST for each individiual dog, but they are common "tools" used in those sports.
From what I understand, the prong creates drive because it gives the owner enough to control to restrain the dog, while pushing them, and urging them on.
Then when you do release, there's a tonne of drive/intensity built up from being held back.
Depending on the size of the dog in comparison to the owner, my personal preference if I ever become involved with any of those sports, would just be a plain, agitation collar.
I'm pretty strong from working with horses, so I dont' believe I'll need that extra control of the pinch.
The agitation collars, just very thick, flat, leather collars, allow you to "agitate" the dog, but limiting the injury that pulling against the collar can incur.
It's a personal choice as I first posted, and I'm sure you know of all of the other options. If you've chosen the prong, I wish you luck and am quite sure you'll know if it's being used incorrectly.
Edit to add: From the people I've spoken with, the prong in ring sports/schH was NOT used for corrections, like a leash pop. Just that extra control when working with dogs that are in that "mode" that in the beginning, can sometimes be harder to control.
Just re-read Melanie's post again, maybe the people around here do it differently, but even with the prong on, if the owners says, the dog is to pull. Rather than, when the prong is on the dog isn't supposed to pull. The lady I spoke with that trains in SchH, uses the prong for control and distraction. Yes, it works because of pain, hence distraction but not used for "loose leash" walking or what not. If the prongs are on it's because they are doing work where the dog is up and raring to go against the leash, the prong is that extra control so the dog can't bite until told to do so.
*shrugs* I haven't ever used a prong, and I don't compete in either SchH or ring sports, just what I've been told by a few people who work/train/title in those sports.