Well finally H&R made a set of springs for the F13 (came out a few weeks ago) and they are on the car. The install was rather easy compared to the F10 M5 where you have to actually remove the inside rear deck and speakers to access the top of the rear spring perches. The F13 is easy in this regard: simple trunk access. The drop is not much more than 20 miles old so I cant give you a full perspective on the comfort or lack of it but the car felt planted and solid at speeds up to 143mph. Of course Ill need an alignment which I will get this week.
Here are some quick shots I took via my cell phone (apologies). Ill get more pics but I think this gives you an idea of what to expect.
Wheels:
HRE P47SC in Satin Black, 20x9.5 and 20x11 on stock tires 255x35 and 295x30
H&R Springs, 1 inch drop at each end per their specs
Side View Not Lowered
Front Wheel Not Lowered
Rear Wheel Not Lowered
Side View Lowered
Front Wheel Lowered (right when the lift came down)
Rear Wheel Lowered (right when the lift came down)