What does the different kg ratings mean ? better ride, harder ride ?

10kg/12kg - Z33FLTA2H
10kg/10kg - Z33FLTA2S

 

Z33FLTA2H - the "hard" setup. Stiffer 12kg/mm linear spring in back.

Z33FLTA2S - the "soft" setup. 10kg/mm progressive spring in back.

Both setups have 10kg/mm linear springs in the front.

I've heard the soft setup feels a lot nicer on the street, but I'm wary of progressive springs at the track. I've heard of issues where the progressive coils stack on each other and become inactive, reducing the number of active coils and suddenly changing the spring rate. I wouldn't want a sudden spring rate change while I'm cornering hard.

I've been trying to research this issue more, but can't find a good answer. I'm leaning towards the "hard" setup to avoid the progressive spring, but I'm not sure if I want to deal with the potentially harsh ride on the street..