Yeap, they stop a lot of the rain / road spray being directed at your upper legs, which not only keeps you a bit dryer but also helps your kit a stay bit cleaner. Obviously being dryer helps you stay warmer plus you get more heat from the engine. If you ride in the winter, closing the flaps will make a big difference or you could alway just put some duct tape over the front of the deflectors
I actually cut foam block and stuck them in the vents during a spring tour of Europe, and it made a big differnce on the couple of wet days I had. I have now bought and fitted the flaps, just not had a chance to try them yet. But I did notice the left hand flap catches on the Givi engine bars I fitted, I've got to squeeze it past the bar
