Upload & Sell: Off
Alternative idea: instead of a new camera, how about finding a more comfortable way of carrying your Nikon and Sigma 35mm? A sling or other such small pack, bag, case or what have you.
with respect to which camera, the X 100 I found too slow to operate, frustrating manual focus when autofocus wasn't working well, and it seemed subject to veiling flare more than I'd like. the new X 100 s will probably address the auto and manual focus issues nicely and perhaps clean up operational deficiencies. as was said earlier, my hope is that the new camera has improved optic as well. if so, it is a camera I could be interested in again. I would not buy the existing X100 myself again.
I have used a variety of really good small cameras, mostly with great Zeiss optics, but my plan now is to goto my Nikon when I want everything but size, and then go to a simpler, less capable, camera when I want transportability first and foremost. With that in mind, by my definition either IX100 would be too much of a camera to purchase just for portability.