it is all in how you treat the trans. i have seen nwc T5's last several seasons in 9 second drag cars, and i have seen people break the good early top loaders with stock small blocks. if you are a ham handed driver, then the T5 is not for you, unless you get one from g-force or other T5 builder. if on the other hand you can drive cars with bad parts and never break them, then go for the T5.
one more thing to remember, the T5 has only so many powershifts in it, so when you break it, build a stronger one.