I have the Falkin Ziex Ze-512's on the back with the Yoko's on the front. The Falkin's are also siped. I never lost traction till I wanted to by using excessive throttle.
The highway was pretty clear except for the last few miles that were slush and snow but I felt very confident on the pass roads with the Falkin's in back. I am changing out the fronts soon as well.
To give you an idea of grip - getting out of the parking space after it snowed all day left a pretty large blanket next to the road. While jockeying it out I actually high centered it a bit but with my friend sitting on the back with the hatch open it crawled it's way over the hump.
I'm going up to Baker tomorrrow to drop off Zedx and Bender at a cabin(don't think Bender posts on zcar...) They're skiing Friday, then I'm going up Friday night, and we're snowboarding Saturday.
I'm slightly worried that Baker might be closed... :sniff sniff: 19" of snow in the past 24 hours.... They were in limited operation the other day because of too much snow. They had their best month of snow in history in January. Over 300" of snow. Might break their previous world record of 1,138" this year. Woot!