Currently, we have one user who barely posted anything on this forum before claiming the N is actually GHB. He proved via PM that he indeed owns bottles of N. In addition, he shows us a report, which can be legit, but can also easily be fake/edited, or being a test report of another substance.
So for now, there is no conclusive prove this claim is true. If it is, surely more reports (probably at Exit forums) should show up over the next weeks/months. Until then, I wouldn't worry that much, because there is still one big issue with this claim: the bottles are sealed, so how would they have switched the substance?
While N is legal is Mexico, GHB surely isn't. As someone pointed out via PM to me, possession/sale of GHB isn't taken lightly over there, with prison sentences up to 20 years, so why would A/D risk that?
That being said, if the claim turns out to be true and the bottles contain a large amount of GHB, you will probably die as well, but I doubt it'd be as peaceful as N, and the report doesn't mention anything about the amount of GHB found in it. But yeah, it surely is possible users who used it never came back here.
For now, I wouldn't worry that much. Either the claim is true and we will see more reports of this over the next weeks/months, or we have someone coming here for fear mongering.