I can back up Floridama on this one with some personal experience. I am currently teaching at the diploma level of the IB (grades 11 and 12) and have taught the MYP as well at schools that have had the PYP so I know the outcome of the PYP having taught the students that have finished the program.
It is highly dependent on the school and how they implement it. It should be a good fit for GT kids because it should be based on growth and projects and cross curricular topics. The amount of homework is not only dependent on the school but on the individual teacher and subject (in some cases).
One of the things that I really like about the PYP is the grade 5 project that they do. It is an open-ended lengthy project that the students present to the school and their parents. They work so hard on it and take such pride in it, it is great to see it build through the planning, designing and presentation stages.
Then, when they get into the MYP it expands this concept as well as marking not on the traditional letter grades of A-F but on criteria based rubric. So, there is tons of opportunity for differentiation, individual projects and some really amazing stuff to come from the programs.
I know the school that I most recently worked at with the PYP did so much differentiation that I was amazed, but it really fits into the IB mind set. I too like the whole student approach to the IB. They focus on the fact that there are certain traits that an IB learner should have - they call them the learner profile and are : inquirers, knowledgable, thinkers, communicators, principled, open-minded, caring, risk-takers, balanced and reflective.
Check out
IB to get more information about their programs and philosophy