I'm a local, but there're quite an amount of foreigners studying PDGE in HK. Sure there'll be some GeoExpats answering you later.
In terms of the reputation of the Universities themselves, HKU and CUHK have better reputation internationally. HKIEd does offer PGDE as well, and they're specializing in teacher training.
If you plan to stay in HK to teach in the future, it's better for you to study PGDE here, coz it's local recognized qualification, which is important.
Cheers, Blom