Sizing of Agon Swim compared to Dolphin Uglies Women's Suits

After reading the reviews of practice suits in a recent issue of Swimmer Magazine, I was rather taken with the fun fabrics of the Agon Swim line. They have a size chart that compares to other brands, but does not include Dolphin. I haven't worn anything except Dolphin in a while and so am not entirely sure of the sizing of the other brands. (No local swim shop besides a small ***'s Sporting Goods with suits only during summer). Should I get the same size as Dolphin? Also any opinions on the different style backs? It looks like returns will be a hassle so I hope to get the size right on the first try. Thanks