I've got a couple of Selle Italia saddles and I've only ever used soapy water (car shampoo in hot water) to get them clean. Like you, I'm near the SDW so saddles often get covered in chalky mud, but mostly from the underside. The decals wore away pretty quickly, but the saddles have remained comfy and reasonably presentable. Saddle soap/polish would be a good idea, or you could try a clear, leather shoe polish to give a bit more of a shine.