I like number 4, only with the "kilt", for a little Roman Character, and maybe with yellow details on the jacket, remenicient of the lightning designs on the Imperial Scutum.
This way its not weighed down, realistic, yet harping back to the good old imperial legions. Napoleonic times were the re-birth of large Empires, and mainly infantry battles, so I could definitly see Rome going to the Legions for inspiration, but without compromising their ability to manouver. In Vietman and the Gulf soldiers have ditched armour to avoid heat casualties. And in Napolionic times Manouver, both tactical and strategic was more important than limiting a few casualties. Remember these guys advanced by walking up to an enemy who was volley fireing at them. Not because they were stupid but because of the importance of formation and manouver.