Heavy weight headsets are typically used by camera operators and production personnel who work in front of a PA system, in higher noise environments or on loud stages. Noise cancelling versions reduce or eliminate the outside noise from making its way back into the intercom system when you press your talk key. The compromise is that in most cases, the audio quality coming from the microphone is reduced when compared to other models.
Custom headsets are a very lightweight and sleek solution for intercom users. Depending on the model, they either provide a custom or a generic ear mold that fits inside your ear and a lightweight mic boom that can be positioned near your mouth. Great improvements in the audio quality that is offered with a custom headset have been made over the years, but users still need to be cautious in how they handle these headsets as the the individual components are more fragile than a typical headset.