I'm another with the same issue. If my hair was consistently grey I'd let it go but, even after several years, it is still only grey on the top of my head, with a tiny bit at my temples. It would look hideous if I let it grow in. I've always had very dark hair but over the last 12 months or so I've started dying it a lighter colour, in the hope the grey won't look quite as obvious. I think it's a vain hope but people seem to like the colour (I'm not convinced!) so I think going a bit lighter is at least complimenting my ageing skin-tone a bit better.
My hair is actually thinning on top so the grey being only in that particular area is doubly depressing, as it does make it really difficult to disguise the thin spots with the grey hair.
I'm at a loss.
3b in South Australia.