mister2
Make sure you're careful for the first 300km or so! It takes a little while for the T1-R's to lose their shine and get to full grip levels. I've found that once they have, they're a great tyre for everyday driving. 
I agree about being very carefull with them, especially at first.
In the past I have worn out 2 sets of T1R's on the rear in the stock 15 inch sizes.
When new, I found them
very tricky for the first few hundred kms with the main problem being the rear end float.
However, overall I found they grip very well in both wet and dry, but I thought the rear of the car still moved around too much for my liking even after they were fully scrubbed in, and trying different pressures didn't help.
But I'd like to emphasize that is just my own preference, because several people in the Vic MR2 Club run them in the stock 15 inch sizes, and they seem happy with them, so maybe I'm just picky.
Some people believe that T1R's sidewalls are too soft in 50 profile sizes to match the rear weight bias of MR2's that causes the rear end floaty feel, however I suspect it may be the outer tread blocks flexing, since as they wear down the problem diminishes until when they are around half worn out the rear end float is much less noticeable.