Nice analysis , one more thing your missing is that Fortuner is longer than prado , in prado when you have the 7th row seats up you have zero space for luggage , in Fortuner even with 7th row up you can put stuff, also Fortuner is slimmer in width and advantage of that is better and easier maneuverability in rush traffic
I had a 2021 facelift sigma which i converted to a 2016 fresh clear TX , and the reason for that was comfort , as this car is used for my fathers office to home commute and driven by a driver slowly, the underpowered factor is felt more on inclines , but man there is a VERY defined comfort difference, the seats are very hard in Fortuner and the small bumps and uneven roads you can feel throughout your body , on carpeted roads Fortuner is perfect,
Prado its a lot more similar to a ZX in the drive and feel .
If I had an old 2010 2012 prado I would definetly prefer a new sigma but since I got fresh car couldn't be more happier.
I even had a a 2021 petrol Fortuner pre facelift and I was not happy with that , sigma is a beast with awesome fuel economy too.
Also prado is seen as a more posh car in general public's perception in case one keeps it for family event appearances
My TX