Facelift trac/slip-cont is much better.
When I had a UK car, I used to turn it off religiously, and I even started enquiring about a device which would switch it off for me every time the car started (didn't want to pull trac fuse).
Now I have a Jap car, facelift, I find it much better. It kicks in pretty quickly, and although it robs a chunk of power, it doesn't rob *all* power like it did in the UK car. The most notable difference though is that it's much quicker to respond. I often get a little flicker of the slip light just to warn me, but don't feel any change to the power.
It still won't help if I hoon it around a bend in the wet of course, but then I doubt anything would.
The upshot is that in my UK car I used to turn it off, and in my facelift Jap car I leave it on.