We used these for the first time at STPR, and I was VERY happy with their performance in the muck and mud. STPR slate-based clay is about the slickest in the world, and these tires did a superb job. The Starion is a real pig in the mud, but I had fewer of the 'uo-oh, is it gonna turn?' experiences than ever before with these tires.
We ran the Z80's, which have the identical basic tread design as the ZE80's, in the mud at Cherokee a coule of years ago, and the experiecnc was horrid. So the extra gap bewteen the tread rows on the ZE80's versus the Z80's really worked. We also went form 17 cm to 16 cm tread width, and I am sure that helped to some degree.
I noted a few other tires in the 'mid-pack' brigade of cars that I am interested in knowing about how they performed: The Kuhmo's, and some L series Michelins's where the gaps between the blocks across the treads had been opened with a cutting tool. I think we all would be interested in feedback on these tires' performance, as well as any others that folks might like to post.