The tread pattern at 4/32 depth seems impressive. It would've been nice for them to show the simulated 46,000km wear on all of the tires for a complete comparison.
This is an excellent point. The depth of sipes and other tread features makes a huge difference in how snow tires perform as they age. And although you can't see it, these characteristics vary a lot between tires. This makes careful comparison shopping difficult. I've commented here before that the sipes on the Blizzak DMZ-3 seem to be full-width right to the bottom of the tread.
Despite the claims in the article, I wasn't impressed by the wear on the XI3. Judging by the tread on the new tire, it has little ability to chew through deep wet snow to begin with, and rapidly loses even that. By 4/32", it would get stuck easily.
Contrary to the claims in the article, the "worn" shot shows this tire loses the "teardrop" feature early, and the sipes are not full-width to full depth. So by 4/32", it looks like most of the function of sipes would be lost. But I guess by the time people have XI3's and wear them down, Michelin will be promoting the superior features of the XI4.
In fact, the shot of the worn "competition" tire shows more sipes remaining than on the Michelin.
The comparison at 4/32" glosses over the fact that some winter tires start at 14/32", while the Michelins start at 11/32" (depending on the size). Buyer beware.