Got my 500PF today!
After about two months, Berger Bros. Camera wound up getting a 500PF in stock for me; it came a few hours ago.
It's a grey day and I've got to do some work so I've not gone out to shoot much, but I've taken a few shots from my apartment balcony.
A robin was splashing around in a puddle. I took a shot with my D500 at ISO 1000, 1/320, f/5.6 handheld; the picture was pin sharp and the robin's feathers were a mass of moire (which is a good thing, at least for the optics). That much detail on a dull day at ISO 1000 (on DX) means that the optics are, essentially, perfect.
The serial number is 2061xx. Can't wait to go find more interesting critters!