R6 vs R6s
I use to sell Yamahas, for about five years. Basically, the R6"S" was the R6 until 2006, when a new "track" focused model was introduced as the R6. Sure, a R6 has a little more power, weighs a little less, has better "track" suspension and all the latest technology, but do not overlook the R6 S. Remember, the rider makes the bike. I can out-ride most on a R6 S, due to experience.
If this is to be your first bike, the most important thing for you is which one is most comfortable for you. Think of the R6s as a road bike first and a track bike second and the R6 a track bike first and a street bike second.