I'm not an S bend fan myself. Perhaps if I were pro and looking for every possible aero advantage at the expense of comfort then maybe I'd go that route. If I'm not able to maintain an aero position for a long time, then it doesn't matter how aero the bars are. I'd rather be comfortable and stay aero than uncomfortable and having to keep sitting up to stretch.

Also, if you trust your LBS to know what they're doing fit-wise, spend the $35. When I first bought my TT bike I adjusted the aero bars myself and rode for about two months before I had time to go in for a fitting. I thought I had them dialed in pretty well, but the fitter made a couple small adjustments and the bars became much more comfortable for me.