Honest question, as an owner of 2 Teslas... How do you know the Highland will be available in 2024 in the US? I think it is a good assumption, but at this point, I don't think anyone has any idea. It can take months to retool a factory, and Tesla may not want to do that with the given momentum of sales, and the available tax credit.
Just like, we haven't gotten the LFP battery that is available out of the China factory (because of the tax credit).
For me, at $7,500 tax credit vs. possibly only half that and ending up with the same non-Higland in 24 is a gamble. If I knew for sure that the Highland was coming out in 24, I would wait, but at this point I haven't heard anything yet that proves it 1 will be produced in the US by 2024, and 2 if it is, that you would be able to actually get your hands on one before the end of the year to get the 1/2 tax credit.
You have to remember a TM3 is a sports sedan, it has a sporty suspension. Also, the most important question is what were the wheel and tire combination that your wife tested? If it is the larger wheels, it will ride harder. My wife has the standard areo wheels, and it rides like any 3 series BMW, minimal body role, and immediate return to ride height (stiff, non-bouncy suspension). It won't ride like an S class MB. I came from having a 3 series and an A4, my 2019 TM3 rides just as good as they did, being sporty sedans.
This is my TM3 with areo wheels, set to 40 psi: