Thanks guys for the input so far. My experience differs slightly regarding the guitars I own. I have two CIJ Fender Stratocasters, one of them is a 1993/4 '62 Reissue model and is finished in Fiesta red. The pickups sound every bit as good as my USA AVRI '62 and the trem block is thick solid steel, same as the US one. I have had to change nothing on that guitar, I even left the cheaper switch and pots in tact based on the old adage 'If it ain't broke, don't fix it'. I now intend to do some recordings to compare to two.
My second CIJ Strat is the see through 'Whiteburst' one that I bought brand new in 2003 from MIJ Guitars in Edinburgh. It was listed as a '62RI 'Premium' model and had gold hardware and has an ash body, making it noticeably more weighty. The pickups were Texas Specials and I didn't like them as they were 'hard' sounding, so I fitted a set of `Tonerider Vintage' which did the trick. I used that one at Shadowmania in 2006, though I had Seymour Duncan Alnico Pro II's fitted at that time.
Again the hardware was exceptional and it had the heavy steel trem block but the larger pots and USA switch fitted. I guess with the gold hardware that's what made it a 'Premium' model. I use it a lot and can't really see or hear much difference between the USA ones and them, only the price.
It seems that there are differing levels of Japanese / Korean / Chinese and Mexican manufacture based on price and competition, but I know some Japanese ones were built better than some of the US ones and I guess I was lucky to get these two. I have also come across the ones with poor trem blocks etc and I'd be interested to know how many others out there got these top of the range examples ?