I just addded M5 CP FSWB and M550d RSWB to my Eibach lowered, non M5 F10 (M5 RSWB doesn't fit on our "lesser" F10's
).
The lowering springs improved ride quality to a stiffer but still comfortable ride. Honestly, the major improvement was looks and not necessarily a better handling car...
The M5 CP FSWB and M550d RSWB on the other hand transformed the handling and steering feel of the car!!!
You can now push through the corners and feel how the front tires loads up and get a proper feedback on tire grip. It's so much more confidence inspiring and provides tons more feedback. It's so responsive to mid corner steering corrections and you definitely feel more in control over the car. You sense you can toss the car around in a totally different way. Turn the steering wheel and the car just responds! The ride quality haven't suffered noticeably. As mentioned above by another member, it might react more to uneven road surfaces that affects only one side of the car. But, it's not a big issue at all IMO.
This is on a regular F10, not a "fancy" M5. But I suspect that the stiffer sway bars of the CP makes a major impact on handling on the M5 as well. Just look at some of the videos online and notice how much flatter the CP corners compared to a non CP M5. That is mainly sway bars.