SO much of it is based on preference/skill. The Gauntlet is definitely very grippy and neutral, but too stable can equate to slow around corners. When it comes to a tail happy car, if you are able to (and this won't always be the case) manage the grip with throttle control and overall knowledge of the dynamics of a car when cornering, then you could possibly end up cornering faster. This game does a surprisingly good job of simulating weight transfer, which is something easily overlooked by those not quite in the know.
This game seems to employ a traction control system like GTA IV, but it kicks in later, and less often. The Futo for instance, fif you lift off and turn, you can get the rear end to swing out, but by hitting the throttle, the weight transfers back and it automatically mitigates wheelspin and let's you regain grip and take off. If done correctly, a car such as this can be far superior to a car that is neutral or understeer inclined.
If you have Forza 4, you can see the fastest people's replays. If you can find a car that tends to understeer - watch the top replays. I guarantee the top guys will transfer the weight forward, get the rear end loose, then get on the throttle slowly, gently, progressively, in order to transfer the weight to the back just enough that it doesn't spin the tires. This can be achieved in GTA.
With all that said, I still love my Sabre, fully tuned, and my race record would suggest I am able to use it effectively.