I think all the full welded Gold irridite finish flexplates (SFI tagged) probably come from the same place, the only "special" thing I can think of is the JW "Wheel", which is heavier and is supposed to help produce a harder hit on the launch.
I can't see or tell any difference between a TCI and a Big End SFI flexplate. Never weighed them side by side.
Flywheels? Man, Steel, Aluminum, different steel inserts for Aluminums, etc., etc........a guy could shop for those for a while, but just about everyone has the same things.