Springs rule. Especially for us 240 pounders because we weigh too much to be overly concerned about a few onces of steel. Go for the comfort. You might want to measure your sitbone width. For me, at 150+mm, a 17 is right at the edge of being too narrow. The real useable web area on a 17/Flyer is about 155mm because of the steel U-frame under the rear and sides. There is no difference between the two regarding actual dimensions. They are the same saddle except for the springs.