I have been using an engineering sample of the 6500 for a couple of weeks now, and I really do like it. I also noticed that the screen "sponges away" a little bit, but other than that, the look&feel is very nice. The screen resolution is a little bit higher than it is on the 7510, as the screen is a bit higher. It is also much clearer, and the touch interface works very well.
After playing with this new meter for a couple of hours, going back to a 2000 series device feels weird. We are all used to the VFDs, but the LCD really does have a lot of advantages. The data logging alone, with the intuitive scrolling and zooming and a huge memory, would be enough to justify the upgrade in many cases. Another neat feature is that you can upload scripts to the meter which also change the UI and add special functionality. That seems to be very powerful. It also has a very good virtual frontpanel via LAN, which is quite useful for remote debugging.
I noticed that the 6500 also shows very low noise, and the (preliminary) specs look very good (better than all the Keysight 6.5 digit meters). As far as I understand it, It does not need ACAL to get full accuracy, and does not have it.
I don't think I should share the photos of the inside or the pricing information for Europe yet, but in my opinion, it will be a no-brainer when you have to decide between the 6.5 digit universal multimeters currently on the market.
There are still some minor firmware issues which Keithley is working on at the moment. The design team has been very responsive to feedback and suggestions during the last weeks, so I suppose they'll iron those problems out before the meter hits the market in Europe. The only thing that I still worry about is that the time required for measurement function changes is much longer than it was for the 2000 and 2010. No big deal for bench use though.