A: As always with this type of question, opinions vary. Some manufacturers and players prefer low-mass tuners and thin, lightweight headstocks to keep the resonating mass of the guitar on the body side of the nut. Others feel that a high-mass headstock and heavy tuners helps to smooth out dead spots and resonances and increases sustain. The answer probably varies from guitar to guitar as well. In our opinion, if a guitar sounds and sustains well, it’s a good one. Low- or high-mass tuners may or may not change the tone and the sustain for the better (or worse).
If you want to experiment, you could clamp a solid mass to the headstock of your guitar and see what it does for the instrument’s tone and sustain characteristics.