Here is a reply from Scaff over at GTPlanet. Scaff seams to know quite a bit about auto physics.
05XR8
If you get the chance to watch Best Motoring videos, you will see some drivers using the handbrake in slow corners and slides to point the nose.
Scaff
On touge runs yes you would be right, in a very tight hairpin then the handbrake can be quicker, on a circuit however its not going to be.
05XR8
These are drivers that race in Super GT, Le Mans, F3.
Scaff
Yet when they race in Super GT, Le Mans and F3 your not going to see them using the handbrake (and most of these racing classes don't even have handbrakes) or deliberately initiating slides (which would get you black-flagged).
The quickest way around a corner is to have all four tyres right on their slip angle limit and the use of a handbrake or slide will always take you over that limit.