I have had a more then a dozen of Jap, Mex and USA strats. I have a Mex and USA sitting next to me right now that and was playing both just a few minutes ago asking what the difference really is. Yes there are some differences but from the mouth of a Fender employee I asked face to face, the mexican strats are made in mexico my mexicans. The USA strats are made in the USA by mexicans. There is hardly a difference to my ears, nor is the feel different.
I had a guy play with me in a band that was the lead guitarist for the Righteous Brothers. He played a Squire that he changed the pickups on and played it through a mesa boogie. He, to date, has the best tone I've ever heard.
For what it's worth, I've decided to sell my USA strat to someone who thinks he knows more then I do and I'm buying another mexi strat. I like having both a single and a humbucker or I'd only own one. There is nothing wrong with a USA strat but for the cost.