The articles on this site say to either keep the throttle on through the turn or brake through the turn, do not coast through. Changes in the power to the wheels can cause you to spin out.
Fishtailing is controlable, or at least it should be. Porsches do this all the time when rounding corners, and in ralley races they have full power slides where all 4 wheels are drifting. It's just a manner of making sure you planned on doing the slide. This is the impression that I get, anyway. I don't have much experience in this area so I'd like to see some experts
come in and explain things better!
Also here's a thought, since the convertibles are heavier cars, then wouldn't this extra weight be over the rear wheels? That's where the top folds up and the motor lies right? Then wouldn't it stand to reason that the convertibles might handle better on the turns? Expert opinion sought!