I'll have to say that in my reenacting days (including docenting at Surratt House) I was one of those corseted women.... they are comfortable to an extent - provided one doesn't lace too tightly! Then you can just "pop the busk" (front of the corset) and undo it; i.e. you don't have to lace each time you put it on - you just lace once and be done with it. I couldn't wait to get out of one, however (and dress back in jeans and a t-shirt!) and yes, I've worn them outside at reenactments in 100 degree weather. I, too left off certain undergarments - particularly the pantaletts - to me, those things are simply horrid!
"The Past is a foreign country...they do things differently there" - L. P. Hartley