Derek,
I cannot disagree with any of that, except for use of the same pre-treatment for the entile carpet.
Uniformity of the finished result is, I believe, an essential aim. In practice, this is not often achievable since the wear and tear on the traffic lanes and shoe-shuffle areas render this an imposibility.
The treatment of non-traffic areas with a product designed to break down traffic grease, I consider to be more than pointless - fibres not 'protected' by a layer of grease may be more prone to any detremental effects of the TLC. Where the pH of the soiling is lower, higher pH pre-treatments will leave a lower residue pH.
I have used acidic rinses for the same reasons you described as I think the 'feel' and 'bounce' of the pile are as important as the 'eye' of the end result, but if the in-tank solution is something like S781 Liquid Woolsafe, I would consider them superfluous.
Rightly or wrongly, my aim has always been to keep the pH of the carpet as close to the desired end pH as possible, throughout the cleaning process.
Regards,
John.
PS. I cannot see a seasoned professional such as yourself falling for any salesmans' chat lines, no matter how slickly delivered