Looking at getting a lightweight flywheel on my spec c

Been advised that as I have a 6 speed the lightest recomended is approx 7.5kgs, as the lighter flywheels have too much material taken off them and become unreliable, something about breaking the lugs off the outside of the flywheel.

What weight do peeps have fitted?? apart from low speed drive ability what other issues can you have??

Thanks JGT