My factory rear knobby is getting worn down awful fast on the road. I've got less than 2K miles on my bike, and it's already a good 50% worn. Since I don't plan on using my 690 for serious offroad (I've got a 380MXC for that), I will surely switch to 50/50 tires.
For the same reason, I don't have any complaints about 1st gear not being low enough. In fact, it's too low for street riding. With the incredible power:weight ratio of the 690, you blow thru 1st too fast (or wheelie out) to be able to "drag" race it efficiently. Better to start out in 2nd gear.
A coworker bought a 690 Duke a month after I got my 690 Enduro. He says top speed is 120mph, but 6th gear doesn't have much pull due to the very tall stock gearing (16/40). I guess that's where some of the compromise on a seemingly "not tall enough" 6th gear w/ the Enduro stock gearing (15/45) went. On my Enduro, 6th gear pulls hard all the way to its top speed of 105.
Considering I use the bike for mostly street riding w/ the occasional fireroads, going slightly taller on the gearing, along w/ more street-oriented DP tires, should be just the ticket for me.