I totally agree that Kiss is the more disciplined live band - they can be knackered as hell, illness and hate each other, but they still deliver to their best abilities. Kind of like Judas Priest who perform with even half the band stricken by flu and feverish.
There is also an indestructible bond between Stanley and Simmons that goes beyond friendship or even brotherhood - I think their mutual Jewishness has something to do with that.
As a group of people, Aerosmith are a lot more volatile than Kiss and there have been numerous phases in their history - drug-induced or not - where they hated each other's guts to the point of the band not working as a unit anymore. But none of that in Cologne, perhaps because the show was obviousl being filmed and recorded (audience mics everywhere), possibly because Lanxess Arena is all new and has a great sound. Tyler and Perry might not love each other anymore (if they ever did), but there is grudging respect. And Tyler went out of his way to highlight Perry at any point, he even had a short set to himself playing and singing a blues number plus Fleetwood Mac chestnut Oh Well. Which he did with aplomb.
Maybe they just want to leave a good impression on that more likel than not last tour and knuckle down to it in a more disciplined fashion than usual.
That said, I will forever prefer Whitford's more delicate soloing to Perry's flash. Whitford is almost Claptonesque in his impeccable choice of notes, every solo a fine piece of music. His solo ratio is only about 1:3 to Perry), but Perry is a lot more repetetive.