I don't think it's the neck. I've always found the LCD-2 to be quite uncomfortable on my head, and similarly with the HE-500. They literally feel like lead weights along my head (similar to the x-ray apron that you wear when getting an x-ray of your teeth at the dentist office).
^ Snuggie version 2?
The Stax SR-007 at ~365 g is still pretty heavy too IMO.