I went from a 925 to a 1520 and noticed the low-light-no-flash capability of the 1520 was less than the 925. This is a pretty equivalent change as the one you are asking about... 920/925 same camera and 930/1520 same camera.
I do have a question in with a Denim user on 1520 to see if the low-light-no-flash situation shows improvement with the new imaging Firmware. No answer yet.
Have not tested taking proper low light shots yet but quick test on my home with auto appeared to come out much brighter than before. Those are now compareable to 920/925. It remains to see how much noise there is in shots.
Probably tomorrow i go shooting again and take low light 4k video also.