My previous was a 1993 240sx. I sold it at 123k miles, still with the stock clutch.
My noise is not the clutch at idle noise that others have complained of.

 

Hi:

I have only 1,100 mi on my 6mt and have not heard any noise like described above. If a car did not make the noise when new, then it should not be making the noise now. There is probably something wrong and the dealers just can't figure it out. They usually don't want to spend the time and money to do so either.

If or when I hear the noise described above, I will insist that the dealer check out the car and verify that the right rear hub nut is properly torqued. Even if they report that it was, it is one less thing to verify.

The 6MT has synchros for first gear. They stopped making cars with no synchro for first gear in the '70s.

The reason it is recommended to not down shift to stop a car is the cost of repair. For most people it is difficult to match the clutch with the RPM perfectly, so the clutch plate gets worn down prematurely. It is less expensive to replace brakes than the clutch, which in some cars requires pulling the engine.