I went to our local D5/D500 event last night, and I ended up placing a pre-order for the D500 (even though I didn't walk in thinking I would... more on that later).
The event was well attended even though it was a weeknight. About 75 people were there. The Nikon tech rep had 3 D5 and D500 bodies each. All were pre-production sample units which he said represented 25% of the total population of such cameras currently in the US. They also had about a dozen current Nikon lenses that could be used with the bodies. An hour total presentation on both cameras then was given and the audience was then allowed as much time as we wanted to play with the cameras and lenses. We were in your average large not-so-well-lit conference room with rows of chairs so were was plenty of targets for testing low-light performance for both auto-focusing and ISO noise. The card bays were gaffer taped shut and, as is the standard rule at this point, no personal cards were allowed in the cameras as the firmware is not finalized on these units.
While I played around with a D5 a bit, I spent most of my time with a D500. I will say for certain that DX is once again a viable format for me. While it was only viewed from the LCD, the noise performance looked very, very good. It's not scientific, but the D500 looked to be able to top my D3s in terms of noise. The comments of some of the pros (albeit paid) that Nikon is using to market the camera appear to be correct. Concert shooter
Todd Owyoung said that he could use 6400 and 12800 "all day", and I think he's not exaggerating. The AF also snapped quickly even with a pointed the camera at a dark corner of the room. The AF is rated at -4 EV, and given that my D3s only works down to -1 EV, that means that the D500 will AF in 12.5% of the minimum light needed for the D3s. While that -4 EV is only for the center point, the rest of the points work done to -3 EV.
I still was planning on only "looking" last night and staying on the fence until production model reviews appear, but then our dealer that was hosting the event announced a one-time offer that was only good for the event. Anyone that pre-ordered a D500 that evening, could bring in ANY working or non-working piece of camera equipment at pick-up and get $100 in rate-in value. That's effectively a 5% discount. Given that it appears that Nikon has underestimated the demand for the D500 and they've delayed the release by a month (the consensus being that they need the extra time to produce enough stock to meet the initial dealer orders), it's likely that the D500 units will be in short supply for some time and will likely be selling at the MAP for many many months to comes. I've heard other dealers at such events offering a free memory card with a pre-order, but not any effective discount. So I jumped. I suppose time will tell if this was just my enthusiasm getting in my way.