Nice! I bought a '15 TEP for many of the same reasons. I actually wanted a trail non premium with katskinz to delete the sunroof, but I couldn't find one.
FWIW - the KDSS is all about cornering and body roll on the road and body stabilization offroad in slow twisty sections. I don't think it helps in any meaningful way on dirt roads, potholes, etc. It certainly doesn't make the suspension stiffer - it's really the opposite - it allows you to have softer springs, with low body roll.
I also have a Lexus RX350 - basically a fancy highlander with a bigger engine. There are merits of both types of suvs for the right owner. If the highlander had a true fully locking center diff with ATRAC - it would be 95% as capable out of the box, better on the street, and probably sell very well. Basically a Toyota quality Land Rover. I wouldn't necessarily want one - but it could be a great option for folks who really don't ever intend to use the last 10% of the capabilities or modify.