I am a little bit surprised to see a veteran with an 02 start date asking this question.
Are you familiar with torque sensing differentials at all or is this a completely new thing for ya?
The Torsen T2R has one full point of a bias ratio above what a Detroit TrueTrac has.
The Torsen is 4 to 1 and the TrueTrac is 3 to 1. In order to do this however the Torsen(T2R version) does have clutches added to it which increases the amount of torque it is able to transfer to the wheel that has more traction.
This means that potentially they can wear after enough racing.
How much is enough? Good question.
They are considered one of the finest road racing differentials you can buy under a thousand dollars.
Even a clutchless gear type torque sensing diff can wear, since friction is still the means used to transfer the torque. Instead of wearing clutches the internal gears eventually can wear out.
At that advanced point most racers I know of will just replace them.
If you would like to learn more just google torque sensing differentials and read about them and see what they look like.
I run a Detroit TrueTrac in my 04 and have loved it's smoothness since day one, it allows me to put a good deal more power down in midcorner than the traction lock would allow me to, and I am able to squeeze it on earlier too.
The performance is very close to the Torsen T2R and the same as the Torsen T2, yet it is or was about 100 dollars cheaper than the T2R when I purchased mine.
1. for resale value, the torsen is a smart move. its the only option available along with the seats and when the cars are used, the seats will be a major selling point. the torsen at minimum is highly perceived as better.
2. my car still has a ford racing limited slip in it. it does just fine. i will probably put the torsen in when the current needs replaced, but there are no signs of that happening soon.