I've just bought what I understood to be a Galaxy S6 G920I model, which is the same as is normally sold in NZ.  However, they supplied a G9208/SS instead without telling me of the substitution, which has annoyed me somewhat.  This is a Chinese market model, it's Cat 6 and has the following LTE bands:
4G
FDD LTE B1(2100), B3(1800), B4(AWS), B7(2600), B8(900), B28(700); TDD LTE B38(2600), B39(1900), B40(2300), B41(2500)

As far as I can see, this covers all of the bands in use in NZ and Oz at present.  It of course starts up in Chinese but that's easily fixed, although I expect that a factory reset will result in the same outcome.  It's also been unlocked.

Is there any operational reason why I shouldn't keep this phone?  The supplier says that they can supply an I model, but aren't sure how long that will take.