Is there any major difference between USP Compacts manufactured in the 1990s compared to those in the 2000s? Are there any major improvements, 'bad batches', or anything of the sort? I've also seen several pictures where the slides on stainless USPs (man. 1990s) are whiter than those on newer stainless USPs (man. 2000s). Is this just because of bad pictures? Thanks!

Take care,
Knight