Regardless of disc type, a light flywheel impacts takeoff from a standing start since it lacks the inertia of a heavier one. You will have to slip it more to get it moving, increasing wear. If you want to drive your car in every day, stop & go traffic & have steep hills like around here I would strongly recommend a standard weight flywheel. It depends on the type of racing that dictates the weight of the flywheel, drag racers like big mass & road racers the lightest possible.
As far as manufacturer's recommendations, I always take them with a grain of salt as they are trying to sell their product. I originally bought the iron setup based on McLeod's recommendation. Regardless of flywheel type an iron disc is always brutal on the equipment, it will eat into your flywheel & PP & is inherently high maintenance. Never again will I use an iron disc on a street car.
Incidentally, Ram is on my personal S-list as they sold me a bum pressure plate once, it was a hemi Borg & Beck & they set the springs improperly. They also did the same on a buddies Chevelle. I tend to like the diaphragm types most, recently I've used McCleod units with good success. I also like to match the pressure to the application, more is not necessarily better.
