Came out of a roundabout a few days ago, and the ASR kicked in bigtime...

The revs became sporadic and the car kept slowing down when i wanted to rev...

I then pulled over and restarted the car and it went away. Is this typical behavior? I put it down to poor traction?

yup sounds like ASR doing it's job and killing revs to kill wheelspin due to poor traction.

Pretty common in the rain!

Pulling over and restarting will have had no effect that a lighter right foot wouldn't also have achieved

My TCS is the same. If i take a roundabout too fast it kills the power and the light flashes. Like you say I think its poor traction.

Especially if like you say your fronts are near the legal limit.

I managed to get ASR come on pretty often in the wet with the Toyo T1R Proxes tyres that were on the car when I bought it. Now hardly ever with new Hankook winter tyres on.

I must be driving like a granny, I never see my asr light on coming out of a roundabout.. Maybe mines broken.. I have (albeit near new) avon zv5s @ about 33psi.

I turn mine off when I get in the car. I find it can be quite dangerous. Such as pulling out onto a roundabout in the wet and hit a drain cover. Power dies and your stick for what seems like an age until the power kicks back in.