It does work in broad daylight but I was referring to fast moving objects where I would need the AF speed of a DSLR.
Actually I was trying to shoot some clouds out of an airplane window & the RX100 just wouldn't focus. I thought the clouds had enough contrast to focus easily... but it was extremely difficult.
Maybe any compact would've had trouble; I'm not sure. I really do love the RX100. The bounce-flash, the larger sensor, the longer focal length lens for equivalent FOV compared to S100 guarantees that your diffraction-limited aperture is higher (e.g. f/4-f/5.6) --making those smaller apertures actually useful, the contrast of the lens (in the center anyway), etc.