What about bokeh?
In the picture above, you can see what bokeh looks like (it is the blurred background in the out-of-focus part of the image), I focussed closely to the ground and therefore the overall part of the picture is out of focus.
I tell you right away, it is not essential. When I started with photography, I thought bokeh is the most important thing and this effect "makes" better pictures. After three years, I came to the conclusion that bokeh makes you lazy in terms of composition. If the main subject is isolated, you lose the ability to tell a story with your picture due to lack of surroundings. More importantly, you have to pay way more for your lens to get a decent bokeh. In the picture above, I stopped my lens down to f2.8, as you can see, even at f2.8 you can produce a nice looking bokeh if you need to.
Does size really matter?
Yes, it does in street photography. As I stated above, the best camera is the one that's always with you. The bigger the camera, the less you take it with you. Also, consider that a bigger camera makes you a whole lot more conspicuous. As a street photographer you should blend into the background like a stealthy ninja.
If you're like me and hate carrying around a heavy camera, look out for a tiny point and shoot or just stick with your smartphone.