Leupold has made some upgrades in the VX-3 line, compared to the VX-III line. I can't say that the S-3 beats the Leupy hands down. In fact, three out of three different people (who do not own either) have preferred the VX-3 (not the VX-III) over the S-3 as far as color contrast and looking into a partial glare.
Not downing the S-3, it is a great buy for the money.
I got the SIII it is the new modle I have had it out twice and I am more than happy with it so far. Im just developing a load rite know. I have shot it out to 900yrds in crappy conditions and it's clear as day. It seams to track good but all find that out once i get a good load it is holding 0.