Hmm. Weird. Sounds like there was nothing that the car could warn you of in this situation.

Think about it, these tyres are so grippy, that by the time they lose grip you are talking some serious cornering forces - once there's nothing to keep you cornering, all that force is going to throw you somewhere in a hurry.

I'd expect that you may have hit oil/ice or other contaminant.

Having driven the car on the very same tyres around the Nurburgring as fast as possible in the wet with the traction control on and off, I am about 95% satisfied with the handling of the car.

I attribute the 'no warning of rear slide' (something that happened to me) to the fact that there is next to no body roll in the car, so you don't feel the lean before it goes. The traction control is more than adequately equipped to recovery the slide as my passengers noted on many occasions. ;-)

Michelin Pilot Sport 2's are the grippiest tyre I have ever driven in my life, and they get my vote of confidence.