Sorry for the low quality of the pictures; you can't take better ones in a mirror, without the flash.-
With peplum -- more authentic, reason to wear the eagle fibulae, warmer. Great disadvantage: HOT! The fabric is man-made; I wanted it because it is so nice and rough.
Without peplum -- cooler, because this dress is linen, somehow cleaner lines. Dunno if a woman of the time would have worn nothing but a long tunic. I might wear one eagle fibula at the throat. I will not, in any case, wear purple Crocs with the costume, but sandals roughly the colour of the belt and belt-pouch.
Here's the dress and peplum, hanging on my bookshelf, picture taken with a flash so the colours are more aurate and the trim can be seen more clearly; all around, not my millitime clock, part of my axe, and one of the orange fluffy pillows Lucifer sometimes bonks.-