CFZ

So give me an example of a matched spring and shock coilover. You would be surprised what you will find with whats out there in the market. Also Most coilover manufacturer will tell you that you can go up or down 4KG. which is about a 447lb difference, how do you match that.

Also with the shock and spring, There is a valving range with the stock shocks. A good spring manufacturer will test out the shock and figure out for us what will work and what wont. Also they will figure out the useable stroke of the shock.

Yes springs are not supposed to settle but if you do enough research you will see that springs do indeed settle after a few months, this is what is called spring sag which is never wanted (Eibach, H&R), better spring manufacturers will never sag. Usually there is about 2-3 days needed for the height to settle and this is normally because of the rubber seats in the tophats that needs to be broken in. because the seating of aftermarket springs are slightly different from oem.

I have seen OEM shocks with aftermarket springs beat the crap out of vehicles with coilovers and vise versa.
Pros of Oem shocks and springs- comfort, and a preset performance out of the box. coilovers will never be more comfortable.
Pros for coilovers- adjustability. and being able to fine tune with your setup.

In other words I don't agree with your post.