I still have my old twin hill pants with a cut above shirts and still on occasion use the zip up sweater. I have never been approached about my uniform and if the day comes that i am, I will switch. I mean come on, take one look at the 140's coming out of the desert and tell me that they don't look like something straight out of a scrap heap. I would think passengers would feel much more uneasy about that then me using a zip up sweater.
Until then, I see no reason to wear those uncomfortable coats. In response to the mainline, I have seen, albeit rarely, an AA captain using the sweater.