I bought the fast road mini tastic ones, they were great, more bouncy/comfy than the rubber ones but I probably did not have the dampers set as firm as they could be. I just decided to go back to the original rubber setup. I replaced the rubber ones when I got the car with the coils, having done very little miles on the original rubbers, so never really experienced what new ones were like. I also upgraded the subframe mounts to solid, and fitted adjustable bottom arms, basically overhauled the front and rear suspension with new everythings..!
Are you looking to sell the springs?
I'd also be interested to hear how your new cones compare to the springs!