What is the difference/benefits/problems in the multitude of clutch/pressure plate/flywheels out there.

I understand the benefits of a lighter flywheel (faster spool up), but I don't know about the other parts (clutch, pressure plate).

One specific question, I see some clutches have contact material all the way around the disc and some have a four contact points in a cross formation. What is advantage/disadvantage of each.

 

Expert I'm not.... but I did have a JWT 1200kg clutch /flywheel combo for my old car. This is what they recommended if you were heavily tunning or any type of FI. Daily driving was still OK with this set-up. It took a bit to re-learn your clutch because of the short stroke and bite of it. I believe this was a 4 puck set-up. The higher the number, the stronger the clamping ability. You have to watch out you don't buy too much clutch or it'll make everyday driving a nightmare. 6 Puck I believe is like on or off. Either you snap your neck at take off or you stall the car. Imagine that in stop and go traffic. My combo was nice but I can't speak for the other companies because JWT were the only people making clutches for my old car. As far as the material on the flywheel, I have no idea. Maybe it's a manufacturing thing. A lot of material probably is wasted making it one complete piece, but wear pads are replaceable. Hope it helps.