Some of the underworks binders will just about kill you if you wear them too long, but for the most part, their binders are pretty good. I used to get the cotton concealer muscle Ts... they're definitely the best, in my opinion. Very little difficulty breathing (you're going to have slight difficulty with any binder; just something you get used to), and it's comfy for the most part. For the past 6 or 7 months, though, I've had to wear a binder they apparently don't carry anymore (which I see now that I'm checking the site, thank god)... I bought it initially only for swimming in, because it's incredibly heavy nylon and spandex, and about the best thing I could think for keeping everything in, even in the water. It has all but destroyed my right shoulder, but I have nothing else... the old binders all ripped to the point they don't work anymore. Sadly, some of us don't have the money to replace our binders every 4-6 months, which is about as long as the cotton concealers last with daily wear.
I would NOT recommend the double front concealer binder... I tried those, and besides being horribly scratchy and uncomfortable, I could hardly breathe. Good luck and whatnot...
SD