I commute on mine on the Interstate (I-10 into Houston, Texas) 36 miles each way. I normally run about 70 indicated (which is a true 65 mph), with the occasionally run up to 80 indicated (about 75 actual) depending on traffic. I get better than 65 mpg that way, and the bike is holding up just fine (should hit 10,000 miles in the next week or so).
Of course, 35 mile blasts are not the same as all day rides.
I went up a tooth in front, but honestly I don't notice the difference. I have what in the States is called the B5 model. Also, for what it's worth, I have a Givi Airstar A602 screen, which does a good job of keeping the blast off of my chest. Freeway riding without a screen of any sort felt like my shoulders were going to be pulled out of the sockets!