I like the 'S'..... I think the sheild takes away from it a bit, maybe that should be a different color. Maybe the 'S' could have more seperation inbetween. I know it is a longer word, but speedbumps in the most important word. I like the icon element.
I am not a fan of the suggestion myself...... clients are strange like that sometimes. The Yellow version is not as clean as the white version... but I think you were more on the right track with the iconic element rather then the font being the logo.