Just took delivery of an OT+ this week and wish I had discovered this thread and page before doing so. I love the truck, except for the ride which is, unfortunately, exactly as others have described here in terms of feeling like driving on a washboard road if you encounter even the slightest road imperfections. The ride over speed bumps and large holes/bumps is actually quite good. The suspension seems completely unable to deal with minor road imperfections. I've owned and/or driven several body-on-frame vehicles before and understand that I shouldn't expect it to be buttery smooth, but it is absolutely miserable to drive at times. As others have said, it is inconsistent. While I only have about 300 miles, it seems to come and go. Yesterday wasn't too bad. Today was awful. Same roads. Same basic weather. No real reason to it.
I'm hoping it works itself out as a few others have apparently experienced, but definitely having some regret at the moment. Test driving before delivery wasn't really an option for me and, quite frankly, while I noticed some odd vibrations pulling out of the dealer lot, the ride the rest of the way home (about 115 miles) wasn't bad, so I figured it was just a fluke.
I do not have the roof rack on mine. That's not the issue for me. I also don't really notice it getting appreciably worse above 70 MPH. If anything, my ride usually improves as I go faster. It's worst for me around town, but also noticeable on the interstate from time to time.