Every clutch is a compromise. Three features are involved: torque capacity, driver friendliness, and cost. These features form a sort of “triangle” that also assumes the space available in the bell housing is not increased. The stock LuK clutch is a valid compromise and “spoils” the driver with good drivability and modest cost. When people “uprate” the engine, they expect to be able to hold the increased power without any sacrifices at the other “corners” of the triangle. That won't happen. South Bend does a fantastic job of offering us more torque capacity with moderate cost clutches for what they can do, and the best drivability that can be attained. Clutch torque capacity depends on the coefficient of friction, diameter, number of friction surfaces, and pounds per square inch “squeeze”. This last factor is often reduced to plate load, but that assumes a reasonable amount of surface area is retained.
South Bend uses the best quality, highest coefficient of friction faces they can buy, consistent with acceptable cost, and smoothness of engagement. As you change a facing from organic to brass ceramic or iron feramic, the coefficient of criction is tremendously increased, and the requirement for higher psi may also increase to fully utilize the better material. For example, the psi requirement of Miba brand ceramic is higher than that for an organic facing. The clutch builder will balance the amount of facing (more equals smoother engagement) with resultant psi (higher psi means higher torque capacity). Less of a heavier friction material also keeps the inertia of the disk(s) down for easier shifting. South Bend uses MIBA ceramic and their own proprietary feramic facing because they work very well and are not aggressive in wearing out their corresponding clamping surfaces (pressure plate ring or flywheel).
A double disk clutch greatly increases holding (torque) capacity, but is hard to fit within the stock bell housing. South Bend has done a great job getting this to work in a relatively user-friendly clutch package. Their dual disk clutches stand up to the abuse of high horsepower, sled pulling, and drag racing. However, they will not be as “transparent” to use as their advanced single plate clutches, which remain the best choices for up to about 600 horsepower at the wheels in non-competition usage. I am very happy with my con-Fe clutch. Some folks feel it is a bit too aggressive or grabby. You can get around that by giving the engine a bit of rpm, like when backing up a trailer, so it won't fully engage and can slip some. Unlike organic materials that slip less and less until you say they seem to engage, the feramic actually does engage positively, and can “chatter” if you don't let it engage completely after the period of slipping should be over. South Bend improves the ability to “slip” this clutch with wave plates or marcel behind the disk facing as a cushion, along with the sprung hub. The con-OFE is another compromise with feramic on one side and organic on the other. Smoothness and ability to slip is closer to an all-organic disk, of course, but torque capacity is less than for the full feramic con-FE. The feramic material is quite resistant to damage from slippage. Organic facings have binding resins in their makeup and the resins will boil and decompose at around 400 degrees F. The process is called “glazing” and severely reduces torque capacity and life of the disk. It is analogous to glazing drum brake shoes on a car several decades ago.
In summary, the choice of a clutch is a compromise. You probably want good durability, the best user-friendliness you can get, and cost to be reasonable but “negotiable” in that best value is more important than lowest cost. The jump from single disk to dual disk clutches entails a a big cost penalty and some inevitable reduction in user friendliness. Make the jump if you need to—meaning you race or sled pull regularly, or make so much horsepower (and use it) that no single plate clutch is enough.