Got a chance to do a little rainy track driving when we did our Euro Delivery, at Spa Francorchamps no less.
As you can see in the video, I could feel the understeer at times if I was too hot into a corner, but because I kept TCS on, the car refused to put any power down until I turned it at least to MDM. Which is when I almost slid out...
That said, I think the car is very manageable in the wet, as long as you're kind to the throttle. I'd keep it in sport or efficient throttle; sport + is too touchy to allow you any light control.