Toyo don't say that any more, they're good up to -9c
They're not sketchy in the winter at all, except on ice where no tyre is any good*. They're rated B-C for wet grip too, which is better than the T1-R and the same as the new T1 Sport. I'm being a tad facetious here, as of course they definitely have their limits, but as long as you drive to the conditions then they're fine.
But yeah, this is about winter tyres not R888s. I can understand why some folks use them, especially in the north, but anywhere south of Birmingham I don't see them as a necessity.
*Unless it has spikes in it, or chains around it.