When the mechanic came back from the test ride on my R after the first service he commented on the front break switch coming on too late. He tried to find an adjustment and couldn't. So he just left it. But I was told that i could claim a new switch on guarantee if it gets worse. So there you got it, no adjustment. You will have to ride faster to break harder, that works!
By the way, he also commented on my rear switch coming on too soon. Never fixed it as the engine was too hot for his sensitive fingers. But he told me how to adjust it myself. And i thought i was paying him for a service?! Silly me.

Rob