My LR w/19's had no vibration issues at all. Not the 38-42 mph or the ~80 mph ones. My Plaid on 21's had the 38-42 mph one but I hadn't noticed it for the first 2k miles I had the car, then I happened to have it in that range at a light throttle opening and I felt it through the accelerator pedal. It was very easily reproduced after that but it wasn't a huge amount.
With the CCB upgraded, I've only noticed it once since then even trying to invoke it on purpose. For some reason when I finally found it, it was greatly diminished. As I mentioned upstream, if I hadn't already known what to look for, and actively looking for it, I probably wouldn't have noticed it.
All in all the car is where it should be. My panel gaps are very good. None really jump out at me. No back seat rattles (just closed them easily). It goes like hell and brakes as well as it goes thanks to the track pack brakes. The handling seems improved and braking is definitely improved as it has seemed to have increased the rear brake bias and even single stops from 70+ seem shorter. Track mode can be a blast. Can't really complain about the overall build quality either.
The SW stack just keeps getting better and better. Seems like everything has finally come together and can't think of another sedan I'd be willing to give my Plaid up for. Still don't like the like of stalks but with the Hansshow wheel (which I like better than the yoke or Tesla wheel), I am pretty happy For the price the Plaid is a steal. It is one of the few cars if something happened to it that I'd go out and buy another one immediately. Hope I feel the same in 50k miles.