I got my gen Sub in 2001, so it was the 904 steel. They just came out with the new style divers extension. Now on my rep I am amazed at how accurate the bracelet is - even the extension works in the same strange way. I think on the oyster bracelet is very hard to tell any difference. As for the jubilee - the gen bracelet is more flexible and feels better on your arm then any rep jubilee bracelet I have seen. It is a dead giveaway for anybody who knows the real one.
To answer Xyphis: I got my Sub rep from CQout 'executive watches' with the ETA 2836-2 and it looks and feels so real, only opening it will reveal the truth.