Recently bought a Yukon XL as a hauler. It has the "smaller" motor but has plenty of power. I had no problems passing cars or entering the interstate at all. I cruised for 650 miles with the cruise set at 72 mph. Couldn't even tell the car was on back until I looked in the mirror. I kept forgetting and I would look up and get startled that someone would be following so closely!
That said, I've been VERY happy with the Yukon. Very plush and built to tow. Good deals can be had too.
