Although you are the friendly neighborhood chinaman, I cannot agree with you. I agree wholeheartedly with most of CI's comments.
Supapimp, what I would suggest that if GSX 1 is the start of any age, it is the start of the MODERN age. Think about that. The Byrne X-mens that were a result of GSX 1 have way more in common with Thor 337 than with Tomb of Dracula 1. And Thor 337 is categorically not a Bronze age book! By GSX 1, the experimentation with different genres had ended and Marvel and DC had stabilized and returned to a more straightforward hero book.
The bronze age is 70-74, if you want to call it a brief age that ends at 74/75 I have no problem with that, that's probably accurate. Books did have a very different flavour in 70-74 than in 75-79 so it was a short lived age.
GSX 1 is the start of the modern age!!!