2020 GLE63S will have the 600hp 4.0TT, 9spd, and 4MATIC+. It will definitely be faster than the current W166 GLE63S. As far as materials, wait and see the W167 GLE in person. Yes, the Cayenne is definitely nicer than the W166 (I like mine for what we use it for) but based on the materials in a W213 E-class, the W167 will be very nice.
I'm looking forward to testing the new one.