I like #4. CA's chain mail together with Prometheus' work is the best!

I don't think it should be rusty. Early Roman army consisted of well-to-do citizens. They didn't spent all their life in wars. War for them was "event". I'm sure they could allow themselves to preserve their armour well between wars and to clean it before campaign. Don't forget that in all times military uniform was something like fetish for humans. Every military man wants to looks as "pretty" as it possible in his uniform.

Their chain mails were relatively new. Because every chain mail is fitted for certain figure, so the armour of father could not be suited for his son and son had to buy his own new shiny chain mail.

Now, think about gameplay, guys. Most of time you'll look at battle from the bird's eye view or something quite distant from units line. I'm sure that dark chain mail with small rings will looks very strange and obscure.

Moreover this new chain mail doesn't even looks like chain mail. Imho. It looks something like warm fluffy sweater... At least like lamellar armour (that's why I think it looks Chinese).