A good PT is good. Doh, this is common sense. Unfortunately,
there are a lot of mediocre or downright bad ones out there who are
in it just for the money. They don't have the necessary knowledge,
and they don't bother to upgrade themselves by
reading/research/learning new stuff. They stick to what they've
been taught at whatever school/certification institute that
provided them with their cert, even if it's not the best way of
doing things.
I have to say though that a good PT is of invaluable assistance.
Having a good PT would cut down the time required for results, and
also impart to you knowledge so that you can continue to get
results after the contract is complete.