RS's always have used blue accents and ST's have used red. It is based on performance model, not on exterior color. Just like the M colors for BMW. Remember that the RS and ST lines have existed in Europe for at least 20 years and the RS for way more than that.
Having driven both the RS and ST, the ST is a much better value. The RS is fun and makes all sorts of fun noises and is technologically more advanced and is an RS, but it costs a lot more than the ST and isn't that much more fun. The RS is still a performance bargain when you look at what cars it can compete against. I still prefer the price point and fun of the ST. I can't use all of the RS's power and performance on the street, but I can use all of the ST.
HBEcoBeast, if you drove it in normal mode, the RS kind of sucks. It feels heavy, unresponsive, slow, and quiet. If the car only had normal mode, I would declare it to suck. Switching to Sport mode changes everything and the car is way more fun. The car feels far more responsive, faster, better steering input, and the wonderful pops and gurgles.