FWIW, I use 680 with a 100 mm stem for fairly technical cross-country riding. But I got my first MTB in the early 90's when short bars and long stems were standard (bar width on that first bike was about 550), and I've only slowly moved to newer geometries. I'm also a pretty small guy (a couple inches shorter than Nino Schurter), so 680 is pretty wide for me. I ride road bikes with 39 cm width drop bars.