personally I think the Bridgy Potenza RE92 where a 1/2 step up from bald tires in the snow. Absolutely the worst thing I have ever ridden on in the snow.
We have had several snow storms and one is currently going on right now.
I can't speak for the Toyos as I don't have them. The Dunlop Sport A2's are decent in the snow. I am quite impressed. We ain't talking jack rabbit starts, but now spinns, no fish tails in the corners and no side stepping on as you describe.
Remeber, these are not snow tires, they are all season radials. They are not designed for snow accumulation over several inches.
The Prius may have been better feeling in the snow because the tire width is less than that of the ES, right?
Steve, we got more snow coming, so be careful out there.
steviej