I had the G1x, also a s100, currently a sony rx100. I bought the G1x because I did not want to take my "stuff" on vacation again. The G1x image quality is outstanding, and I would say very close to your 5d. What I found , for my purposes, is the g1x was just a little to big, meaning you need a small bag, I had a apex100, so it's like bringing a camcorder. I ended up always leaving it home, and grabbing the s100. The s100"also takes great pictures, lowlight it struggles a little. I ended up selling both, and even though I am a life long canon guy, bought a sony rx100. This camera fits in your cargo shorts, jacket, what ever and is very close to the g1x image quality. On reviews, it is suppose to be better, my eyes it is slightly less, but debatable. I basically use the sony for everything, throw it in my jacket going to family functions, going to the beach..vacations...we went to Disney, on rides it was in my pocket instead of have this big bag and worried it was going to get wet. etc...etc....my 7d is down to sports, not much else.