Hey Sam,
It takes only a little imagination to understand the potential of perfect pitch in the hands of a creative mind.
You hear something you can write it, you think something you can write it, you read something you can hear it, you read something you can vocally reproduce it.
Absolute pitch - no limitations, you're not hide bound to traditional instruments but can hear music everywhere, in every sound. Therefore every possible pitch becomes another sound in your musical vocabulary with which you can express yourself and create musical dialogues.
If the aim is to only have your child be able to reproduce the tones that are pleasing to you you are cutting them off from choosing their own musical path. True creativity comes from expressing yourself musically not expressing yourself musically within these hidebound rules. That is how we stagnate. I think there is definite danger in only training in traditional music or only western music or only contemporary music or only anything. To evolve musically we need the next generations to have two things - the tools, and the imagination to use them.
To carry the language of music with you in your head....a wonderful skill. Combine this with creativity and there are no musical boundaries.
As for the trebellina DVDs I don't know why they'd include someone singing off key - similar experience with YBCR when the little girl singing changes key half through I'm a little teapot. It drives me up the wall.
Having said that if you have never been sad can you truly appreciate happiness? If a child only hears excellent pitch can they appreciate it and value it or even recognize it? I don't believe that all musical experiences should be perfect. It gives no spectrum to the child as a reference point and no appreciation for the work that has gone into the acquisition of the skill nor a visualization of the path and journey to get there.
Sorry to drag on, I just feel that as a whole musical education misses the point.
I just believe that a child who has been exposed to good music from in-utero, would be able to develop rather musically already. Just like Mozart. Would his parents have specially given him 'perfect pitch" training? I doubt. But Mozart was exposed from the time he was in the womb.
sam