"The smaller the f-stop the more light gathering capability"'
To clarify this point, when you read photo reviews "small F stop" means something like F11/16/32, that is 1/11th and so on of the available light (F1)
In this case Greg meant a small number,(referred to as wide or large F Stop/aperture) in this case F1.8 /F2 compared to the more common F3.5 and smaller.
Low light capability is also determined by the type and size of the sensor as well as the firmware, in other words how the on board processing chip handles the image.
So having, for example , two lenses with the same specs, one camera can still give you better low light performance than the other.
When DPReview does the final comparison all will be revealed.
(most compact weatherproof camera use the 1/2.3" sensor )