A couple days with the new XK and I'm noticing some definite differences between the two. The 5.7 throttle is touchy. The 4.7 you can give it a bit of the long skinny and it reacts in a well behaved manner. With the 5.7 if you give it a bit of gas you have to be very careful as it will want to jump. Not the stalled engine sort of jump it just wants to get moving...NOW!

The engines sound very different next to each other. I may have a pump or bearing starting to wear on mine there is a slight whine from mine but not enough that you would hear it and think "Ah ha! That's an alternator/power steering pump/water pump etc.."

The wife's doesn't have the heating/cooling in the back. I wish mine didn't either as that space could be used for something more useful.

I ordered rubber matts from weathertech (thanks for the link Sal) My wife has a cargo net...i want one too you don't realize how useful they are until you've had one and then you don't. I found one on amazon for $23.

The best find so far is new buttons for the key fob. C'mon look at your jeep keys, those things are nasty! You can shiny new buttons for $7. https://www.ikeyless.com/vehicles/Je.../2006/1001449/
I ordered two because I'm sure as soon as the wife sees mine she'll want one as well. I think this is going to be the biggest problem with the whole his and hers thing. When I find something cool I have to double the price :-(