Even you can admit, Smiffy, that the current shirts aren't obviously green from any sort of distance
In that sense, proper green to me would be anything that is actually obviously green. Unlike the current shade.
Brighter green is hardly an alien colour to anyone, is it? If you look around Home Park, the youngsters you speak of that aren't wearing the official shirt are likely to be wearing lighter green adidas, Nike etc sportswear as an alternative means of support and fitting in. Quite simply...lighter green looks better, is more green and at the very least would sell plenty of shirts as a nice change. No brainer.