He is 13 years old and needs an low light capable compact cam. Shooting indoor @ discos,...
It should be compact, as he is want to take it with him when he goes flying and doing much sports.
I would not use anything but FF in light that low. A 1" sensor is going to be a big compromise. With people moving in a disco, you need reasonably high shutter speeds, so ISO levels of 6400, 12800 and higher might be needed. Of course, he can possibly get some sort of image if there is a spotlight on the subject, but to capture the colors in low light is just plain difficult.
Also be aware that any laser light show will ruin the camera if the beam hits while the shutter is open. Its a common issue for newbies who try to take video at a laser light show. Warranties don't cover things like that either.
Thanks. He knows this problem. I know, that an 6D would be better. But to carry this Cam with the 24-70 2.8 around, is to much risk. Better an small camera. Lesser risk.
I understand the desire to want small, but if he wants to use it in low light, plan on returning it.
I would suggest a wide aperture f/1.4, f/2, or a 40mm f/2.8 over the 24-70mm L. I bought a G1 X MK II as a compromise, its reasonably small, not tiny, has a large almost APS-C size sensor, can do ISO 3200 in a pinch, and has a fairly large aperture at the wide end of the zoom.
I've yet to try it for low light events, however, here is a theater shot of a stationary subject with my G1 X MK I at ISO 3200 1/25 sec f/5 (New model has faster lens) Its ok for prints 8 X 10, but at 1:1, detail is definitely lost.
This is a jpeg processed from a raw exposure. I went light on NR to retain detail.