Disadvantage: Surprises if it grows back in.

[Jay]

Because I recently moved to a cold northern climate, I'm keeping the hair at a #2 clipper for the winter.

What do my eyes see? Suddenly a lot of grey hair sprouting up.

[Razor X]

I'd say this is not a disadvantage at all.  Quite the opposite, in fact.  Keep your noggin shaved and you won't see the grey (and neither will anyone else).   

[SLYinKC]

Look at it this way.... It'll be harder to see the shadow.

[warhawk]

I'd say this is not a disadvantage at all.  Quite the opposite, in fact.  Keep your noggin shaved and you won't see the grey (and neither will anyone else).   

DITTO

WARHAWK