X100S for only camera?

I am a hobbyist, where my interest in this hobby wanes and waxes.  I am looking to get back into photography, doing mostly in-city walking around shots of people, interesting things.  I am really fascinated by low light city life pics, using whatever available light, candles, lamps, whatever-- more than pictures of rolling hills and trees

Would you think the fixed lens X100s would be suitable for an only camera setup? I have a Powershot G11 (hand me down) and a Nikon 4500 (really old).  When traveling, I know I would only take 1 camera.

I don't think the X20 is enough of a jump over the G11 to justify the cost.

I was looking at the NEX6 and Olympus EMP2 also, but the x100S really grabs me.  My only fear is the the fixed lens.  I don't want the XE1 or XP1 as I would wait for the next gen at this point.

SO any ideas?  Thanks!!