The other benefit (if you look at it this way) of S mode around town is a very quick tap on the break will force a downshift and you can use engine braking to slow down. I find it very handy when the traffic's light enough that I can anticipate lights up ahead. Don't think it would do much for you in complete stop and go.
2012 Focus Ti Hatch | Ingot Silver | 401A, Nav, Winter Pkg, Moon Roof, Parking Tech. Pkg
Build Date: 12/2/2011 | New APIM: 4/4/2012
MFT: Factory v2.11, 3/14/12 USB/Web > v3.0.2, 9/24/12 USB/Web > v3.2.2, 1/24/13 USB/Web > v3.5.1