Cones vs. factory spikes?

Has anyone done any A-B testing for various speaker cones? Currently, my KEF REF 4s (120 lbs each, ported base) have the factory spikes. Before spending big bucks on Orchard Bay cones (used on Talon Khorus and recommended by my dealer) or Black Diamond Racing (why is their web site is abysmal?), I would like to know what others have used on the bottom of their speakers and if they make an "audible" differnce. Rest of system (for 2 channel) is: Aranov tubemonos, firstline pre, Sony SCD-1 (on order).