What they are missing is the phalerae that is worn over their armor. Any centurion should have something there in either gold, silver or bronze. It was held on with leather strapping in a grid pattern. I am not sure if I have the energy to attempt to model this onto the figure. 15mm is kinda small for my fat fingers to make such a small change. I grew rather frustrated trying to mod my padre figure for my Italians in 15mm. I don't think I will try it here.
I plan on getting a pack of the QRF signifers and possibly a pack or two of their auxiliaries as well. That should give me lots of flexibility.