I lowered my DR to B yesterday since Suzaka was so dirty earlier it became impossible to have a race. After 2 races my SR had dropped to B. Racing as DR.B is much better. I'm hovering around 28K DR, pitting in lap 7 when I got too close to DR.A, and it's bliss not getting penalties for other's mistakes or dive bombs. Sure there is still the occasional misjudged penalty yet it was very easy to get back to SR.S in DR.B in those dirty races. Got a clean streak going at the end as well.
Today on Mount Ramarama it paid off again. In one race I got bumped from behind no less than 6 times, bump passed on T1 and driven into the wall on the mountain section. Not a single penalty for all that! Despite no SR Downs, I did lose 5 SR in that race. The 2 cars that were bumping into me stayed blue, 2 vs 1 I guess. However had I been DR.A that race would have dropped me to SR.A or lower with a bunch of penalties. The only penalty I got was getting bumped into the one little 'shortcut' at the start of the downhill, too close to the wall. And someone crashing and bouncing off me. Yet so much better than driving as DR.A.
So for now, I won't bother with qaulifying, have fun races making up plenty places and not worry about getting hit from behind anymore. The worst that can happen is getting promoted to DR.A again. Matchmaking is exactly the same anyway, same familiar faces. A+/S to D/S rooms.