The T8 is worth it to me, mainly due to tax reasons here. There is around 8000 euro in money off by government grants. Makes a D5 R-Design and T8 R-Design specced the same (bar extra bits you get on the T8 _anyway_) around the same money.
The 'hybrid' mode in the T8, default drive mode, lacks a clue full gearbox when you really want to get moving. Switching the drive mode to 'power' it's perfect. I see a polestar upgrade in my near future to avoid this.
But at 407bhp as it stands, or 427bhp after polestar it's a really great car. I love when I floor it I get the whine of the super charger and overtaking 4 or 5 cars in a row is a simple task. In my Audi A7 I'd be panicing near the end. A single gear change in the XC90 and I'm past them.
At idle the engine is a little noisey, but nothing crazy. You can't hear a thing inside the car. So do I care? No, I do not! I've been up and the motorway here around 100km each way and the drive was quite pleasurable. And I come from the V6 Diesel world of Audi

, I don't think I'd return but time will tell.
_edit_
Forgot to mention that the T8 sees 60mpg real world on short trips < 50km if you have a full charge. On longer journeys 30mpg isn't unheard of. Depends on climate control and all the rest but after less than 1000km I'm pleased for the most part with the fuel efficiency. As an FYI the A7 V6 TDI would do around 40mpg absolute best case, but was typically 30-35mpg. And often it was 24-26mpg on commutes to work especially in winter months.
I can see the pre-conditioner in the T8 increasing year round fuel efficiency long term.
My 2c.