Off, as tiniest bit of wheelspin is not a bad thing - though on the later cars, it shouldn't make a massive difference was you should be well on your way before it starts to kill engine power (it attempts to brake spinning wheel first) if you know how to launch a car properly.
My 3.2 is still pretty bad with TC on. In my experience, it will have a go with the brakes if you are applying the throttle gradually and everything happens slowly (worked great the when I had to tow a trailer out of a muddy field). In this instance you can hear the ABS pump fire up and feel the brakes binding.
If you're trying to "launch it", however, it just falls on its' nose at the first sign of any slip. If you don't come right off the throttle at this point the power comes in again quite violently, and that unsettles the back end again, so you kangaroo up the road. I can certainly do better with the TC off. Having said that, apply full throttle smoothly in a straight line on a decent road surface and you won't be anywhere near breaking traction on 235s, and you'll get down into the 7's 0-60.
In a manual, of course, the temptation is to dump the clutch a bit too vigourously, and you can always brake traction that way. [smiley=evil.gif]
Kevin