The bikes now come with HGS exhausts and Vforce reeds when purchased and better carb needles and jetting ( included in the price). Yamaha have a price reduction and specials on for these bikes at the moment, and the deals are extremely good. Strong rumours in Europe saying the new YZ85 is almost here and maybe a yz65 . The current yz85 and yz125 with the HGS and Vforce fitted, are very good value and race ready. There are also very easy mods ( not expensive) you can do to the YZ85 to make the powerband very good for MX and Flat Track. Not having a powervalve doesnt effect this bike at all, if tuned to suit racing conditions.
The YZ85 is great to transition to from a 65cc bike, and the YZ125 has always been a rocket after adding a HGS and Vforce.