I am a 34dd, almost a 34d and I measured 30 in underbust and 36.5 chest. I decided to get the Medium, but I was between sizes for the Small. There is still a medium bounce, which I expected since this does not have a wire. It doesn't hurt when jumping, but it is noticable. I think I could have gotten away with the Small and had a little less bounce. I love the look and feel of the bra and the color, I got it in cloud.
My one criticism, is that the removable cups are small, imagine b cup size trying to fit over a dd.... So as the bra is stretched over my area, all of the lines of the cups are completely visable, especially because the bra is white, and I dont like that. If you have smaller chest, you may not have this problem. But since this is in white and I have a larger chest, it is extremely visable, creating circles within my boobs. Every time I take off the bra, the cups also move all over the place. My only solution is to take the cups out and put them underneath the whole bra and on top of my boobs, that way the cup lines are not visable and the nips dont show. I am willing to work with this though because I love the way it feels and it is so hard to find a beautiful white sports bra. I tried this on when my husband was home and he said it looked so nice I should just wear it as a top with jeans!
Katie, I would suggest for future bras, that the padding is sewn into the bra, or at least made larger so the lines do not show.