Here are a few images demonstrating the effectiveness of the "Group" AF mode on the D500... for BIF I personally love "Group" mode and have enjoyed a very high keeper rate. Love it.
D500 w 500 f/4D AF-S (Non VR) ~ All handheld ~ Processed in PSCC
I got bored on a rainy dismal day this week so I took a ride to see if the Osprey were fishing and I took this shot just to see what a shot at ISO 20000 looks like. It's a fairly big crop but it doesn't look half bad for the web.
Flat light and high ISO push the DX sensor to its limits. That said, ISO 2200 on the D500 is like ISO 800 on the D300 in terms of color quality and noise.