I think the Murmillo is my favorite, also. If you tell me that's a fish (it should be) on his helmet, it's definite!
Will you be adding little pops of brighter colors on e.g. feathers, skirts, etc.? For instance, I think the little bits of strong (though not bright) green in the very warm, largely orangish-red color scheme of your recent Khorne figures really adds a lot of visual interest to those models. I think these gladiators could be even a bit more flamboyant than the fantasy unit! Remember, these were the NFL/Premier League stars of their day (chariot-racing serving as NASCAR-/Formula 1-style entertainment). Like our 'heros' they did dress up in ludicrous colorful uniforms. After all, they realistically might die in them, so they wanted to look scary and cool! At the very least, the dealers, fight brokers, and gladiator schools that owned and trained fighters (often) play essentially the same role in shaping public opinion as they did 2,000 years ago. Chased relief sculptures of fish on murmillo helmets (which is a decorative, rather than a practical design) speak to the same basic phenomenon.
Anyway, I know you are a true believer in the church of painting realism, though you're very tolerant and appreciative of other approaches, so I just want to give my professional blessing to you going over the damn top on these bad boys! Win the historical category this year, John... we all want you to grab the trophy, bark out "Are You Not ENTER-TAAAAINed", and rush off with Janet in hot pursuit as you rush to the airport to catch a flight home...