I went with 15% Xpel XR Ceramic on the front two windows and 70% on Xpel XR Ceramic on the windshield. The tint looks dark from the outside but I can see perfectly fine looking out - day or night.
You can see a different hue from the two fronts vs the rear. Everything looks blueish from the tinted windows and brown from the factory windows. If you wear polarized glasses you'll see a rainbow effect on the two front windows/windshield.
I had 20% on my old Evoque with no front windshield tint and that looked as dark - I am thinking its because the DS has a larger rear windshield, so I might just get that tinted, plus it helps cut out the light from when people drive with their high beams on.
I got mine tinted using 25%. The installer had a tool that measured what the back windows are and it came to 22%. I do have the dynamic and black package. Here is a before picture and a couple after pics. After the tint cured for a few days it matches really well with the back. Made a big difference to the look of the car.
I did 40% on the front and 60% on the windshield. 3M Crystalline has very similar hue with the stock privacy glass in the rear. The only color difference is when you do car wash. When with water beads, the tinted glass starts to show a sort of yellow/orange spectrum, which is also happening with Tesla X's roof glass.
The California cops have never pulled me so far. I wish I would have done it with 30% on the front.