At Ed Roman Custom Guitars We have opted to use real hardwood overlays on most of our headstocks. Most companies, PRS, Gibson, Gretsch, Dean etc simply use a very thin piece of plastic which costs about 0.6 cents.
While these super-thin plastic overlays look okay, they don't do too much for the tone or strength factors.
We use a solid piece of Ebony, Rosewood or Holly on our headstocks that cost us close to 5 dollars precut.
This is one reason we can guarantee our headstocks not to break!!!
And one reason we have noticed that Gibson headstocks are designed to break.
We also use a volute on the back of the neck which also adds tremendous strength to our necks.
In 20 years we have never had one neck ever break this way