Hi,
nice to see this forum coming back!
I changed to the 9520 from my 9560. I got the i9 Oled version and quite like it. I got the i9 version because of its overclocking/undervolting capability and set a -110mV undervolt via Throttlestop. Sadly virtualisation has to be disabled as Dell did not put out a BIOS that let you set voltages yet.
Speed shift has a toggle in Bios so we don´t have to hassle with EFI shell. I tried that and extracted Bios but something seems to be different this time. I could sent the file if someone like to have a look.
It´s a really thin chassis but Dell(or Intel) seems to have improved thermals/throttling. In my 9560 it was quite hard to get it not slowing down PL1 limits.
Only grain of salt for me is the Bios missing options for the unlocked CPU.
Edit: I repasted with Kryonaut and put in a 2TB 980Pro as second SSD (you need this second heatsink from ebay/amazon/...)