I will always take a Flightsuit for trooping over Coveralls... and here is why....
Flightsuits have the adjustable wrist/ankle meaning that you can cinch them down for blousing or just to fit neatly under your guantlets. The multiple pockets are great for carrying a variety of things. I put all of my annacronistic things (EI; ID, cash, credit card ) in the thigh pockets. Also Fliightsuit have the ventilation holes in the armpits and crotch, just a small detail, but very welcome in the TX heat. And finally, the small bicep pocket on the left arm of a flightsuit is a perfect place to hid your voice Amp.

I put my voice amp in the bicep pocket, and run the mic wire up the sleave and through the neck hole then up to my headset. Great way to hide it, and still be able to take your bucket off.
Captain Daves is great value...luckily, i just need a black flightsuit, which i can get for $40 at the local surplus
I have lived in Coveralls mst of my life, working in garages and in the navy. The Polyester doesnt breath as well as teh nomex or Cotton blend flightsuits.