The 19" width EVA pads from Gossamer Gear are too narrow for hangers, been there, done that myself. Get the 24" ones from other suppliers. If you already own the GG pad, use it on top of a cheap, smooth surface foam pad.
I agree that the insulation value will be about the same for any flat surface, closed cell foam pad of the same thickness. The waffle surface will let more air in, both summer and winter. That air circulation is good in warm weather.
I like Mountainfitter's new, thicker EVA pads for the width, the light weight, and the softness. Yes, the 1/8 inch foam is just too flimsy to work well.