G1X vs S100 - How much Image Quality difference is there for real?

Hi

I just returned my G1x,mainly the size was slightly too large and the general speed starting grating with me,i picked up a LX7 and have been very surprised at the IQ,it;s very good and matches the G1x at low iso,after 400 iso things fall apart,but the lens is f1.4-2.3 , 2 stops and morefaster then the G1x at longer zoom,i suspect the G1x is a good 2.5 stops better in the sensor dept  ,i was worried about using a titchy sensor camera after the G1x,but the LX7 has been a revelation,for the record the G1x produces beautifull iq right up to 3200 iso.

Prev tried the X10,not impressed,nice colours,but pixel sharpness is terrible and raw files are weird.

Good luck