For my style of street work, the 5D3 & 1D Mk4 stay at home and the S100 comes out. People have a lot of significance on a "big" dslr and you may not get as much agreement with the bigger pro-looking gear. It's all about perception. In a legally suppressive and paranoid city like London for example, you definitely leave your DSLR back at the hotel! You just have to be a bit smart and be appropriately informed about the local culture, laws and attitudes towards shooting in public depending where on the planet you are shooting.
There is no denying the IQ is way below dslr level when shooting with the little S100, but I come from the school where a prime consideration is that Content is King and this does apply completely to my style and interpretation of street photography. I'd rather a brilliantly caught moment done with an iPhone to a relatively dead, though technically perfect, mistimed shot done on a 5D3 with premium L glass. Content is King.
When the new mirrorless Canons ship, and then evolve a little further, you'll be looking at a street kit that even the street photography "God" Cartier Bresson would show interest in.
Street photography is an entirely different experience to how it was even just a decade or so ago. We're in the post 9/11 world. Suspicion, and the attitude that photographers are child snatching bestial terrorist operatives, plus the long arm of the law have diminished what could be described as one of the purest forms of photography. Remember, if you plan to use any street images commercially or plan to show them as fine art, protect yourself by carrying a dozen or so model release forms in your pocket or bag. If you can't get agreement, don't use those shots for anything beyond personal use.
You may see this as convoluted and confronting, but it sure as hell improves your personal communication skills!