I don't know Woody. I think sometimes handlers out-think themselves. Frankly I think building a solid dog is easier than a lot of people might be willing to believe. The dog has to have what it takes, of course. Assuming the dog has the right genetics to be at least a decent working dog then the training is not that difficult. In fact in my limited experience it's not so much about the difficulty it's about having the time to invest in the dog.
For example, if you're trying to teach the dog to track and you go out two or three times a day and have the dog track someone that dog is probably going to end being a damn good tracking dog. But if you only train once a week or once a month then that dog is not going to have the benefit of the experience the more trained dog received.
With the bite work I think it's better to get the dog to bite for fun before it bites for real, if that's what you mean by "prey" work. My dog wasn't trained under that philosophy but my next dog will be.
From initially learning the ultra-right wing approach to dog-training and then being exposed to everyone else my feelings about training are no longer to the right but nor are they in line with the majority.
My feeling about raising and training a working dog is to keep it as positive as possible, make it fun and make sure the dog is never pushed too far and that he always wins. Take the dog everywhere and put him in all types of controlled situations where the outcome is always guaranteed to be a good one for your dog. Build that dog's confidence and make it absolutely at home with any situation, anywhere and that dog, again assuming it has the genetics, will be a kicking-ass dog!
Again, I don't think it's as much the expertise as it is investing the time to do it. A brand new handler probably can't do this. A committed handler with experience and with some good direction definitely can!
The biggest challenge is the decoy. Many experienced decoys I've met are one-dimensional in their "training" whether it be a Schutzhund background, French Ring, etc. and therefore are not (usually not) open to other decoying methods. And then you'll have different decoys with their own ideas on how a PPD dog should be trained. My personal approach is to find people who are willing to work my dog the way I ask and I am willing to work theirs in the manner they prescribe.
In training a PPD dog I think you need a decoy who is willing to roll on the ground, scream and be a hell of a great actor for the benefit of the dog's progress. Most decoys are too proud to take direction or advice from a handler, let alone roll on the ground or, lord forbid, scream as if the dog is actually hurting them while the dog is administering a level 10 bite into their protected rib-cage.
Ok Woody. I guess I want on a tangent and got a little off-topic but hey, it's been a while! Anyway, for what it's worth, that's my 2-cents!