I know nothing about the seller, but it's hard to argue with over 37,500 sales at 99.9% positive.
Besides the truss rod placement, the American necks have carbon fiber reinforcement and the Mexican necks don't. If you're also asking about tuners, the American necks do have higher grade tuners but the Mexicans are certainly usable.
In recent years, I've noticed that the American necks seem a little thicker front to back than the Mexicans, but that may not be true in 2008.