Just done it yesterday, dropped 40mm on standard shocks, i cant decide if its too harsh, on normal roads its ok until you hit the potholes and then you know about it, but long motorways should be ok since the surface is usually quite even.
As for messing about on the twisties, it is harsh but the unbelievable better handling more than makes up for it.
The car also feels a lot more rigid which i like, makes you feel more like part of the road.
My dad was against me doing it, and i took him to look at a car today (for him not me) and he complained the entire journey.