From my limited experience with Hyatt:
Grand Hyatt = Great CP, low-end IC
Park Hyatt = a bit better than ICs
Hyatt Regency (where I stayed most, even before I joined GP) = CP. It is def not up to an IC.

There are some bad apples in each of the chains. For PC this is true for probably everything but IC - I can't think of a really bad one.
Hyatt Regency Mainz - I'd take a new HI over that any time....
Grand Hyatt Hong Kong - absolutely no comparision to the IC HKG
Park Hyatt Hamburg - excellent property, IC Hamburg is probably a "bad apple" and as low-end as it gets

etc. etc. etc.

Overall, this thread might lead to some very emotional discussions...