Maybe i'm the weird one.
I was reading up on the "short term right to reject". It does tend to suggest that it would need to be not fit for purpose. It would be pretty ****ty for me to try that. Also, as a friend of mine in the car business pointed out, the car now has one more owner and so it's value has changed. Also I traded in a 2007 LS460 for it. They were sending that to auction so that's presumably already gone.
And yes, my LS, with 114k on the clock was way more hushed and refined too. Then again, new it's nearly twice the price of an RX450.
For me it was the case that the initial drive home on the M25 and M4 was very pleasant. The following day, driving it around locally, every pot hole and crack in the road was extremely evident. You've got two RX's and an LS. Surely you notice a big difference, no?