I did the full KW's on my E63 m6- not a bad thing to do since I had full control of the height and the handling improved. But in reality we are talking about a 4300 lb car (F10), no matter what you install you are not going to change gravity. These cars are flat out pigs and unless you do dedicated tracking of the car I think the KW's are overkill. H&R got it right with the F10--- keeping the drop within reason to enhance form and yet keep function. Almost all of the oem handling characteristics are retained (good thing for me) and you get to reduce that small but unsightly gap.
My Black Series has coils from the factory- better handling yes but loss in comfort. The car also weighs a lot less than the F10 so the coils serve their purpose better in allowing me to toss the car around more. Having owned 6 M's I have always liked the OEM feel of the suspension in regards to chassis feedback, steering, yaw, body roll at lower and higher speed turns. I just didnt always like the small extra gaps they had.
With all this being said I like the KW sleeve idea. I have had two sets of KW sleeves on my E63TT wagon and my CLS63TT. I liked the way they felt along with the stock amg performance dampeners. The only problem with these cars is they have the airmatic suspension in the rear which is not optimal. The key with KW would be in the spring rates. Id like to see how compliant or stiff they would make them. Normally H&R is rather bouncy but thats associated with larger drops. I couldnt even tell my car was lowered with such a limited drop on the F10.
2016 BMW M5 Alpine White
2016 AMG GTS Edition 1 Selenite Grey
2015 Lamborghini Huracan Bianco Canpus (Matte OEM)
2015 Bentley GT3R Glacier White
2012 Mercedes Benz C63 AMG Black Series Obsidian Black