I don't think the width of the saddle in back (which is where your sitbones are, and where the saddle width is measured) will make much of a difference to chafing in front - that's more a function of cut-out or not, width of cut-out (I like a huge one, a narrow one just pinches me), saddle tilt (very important, just a tad down in front can remove all "front pressure" but can put too much pressure on your wrists), shape of the saddle (horisontally flat or curved) and width of the nose. Try looking at what you're actually sitting on when you slide forward and feel some relief from the chafing.
Winter riding is much less about badassery and much more about bundle-uppery. - malkin
1995 Kona Cinder Cone commuterFrankenbike/Selle Italia SLR Lady Gel Flow
2008 white Nakamura Summit Custom mtb/Terry Falcon X
2000 Schwinn Fastback Comp road bike/Specialized Jett