Well, I finally did it. Last week I picked up a pair of Schwalbe Ice Spiker tires. Deep knobs, soft rubber, and 304 tungsten-carbide tip spikes. Pricy but, as I discovered, worth every penny and more.
I've been ripping in up on slippery compacted snow and ice, including some steep single track climbs and descents, and I can't wipe the grin off my face. I have better traction and less wheel spin on climbs now than I have during the summer... and the stopping power is unbelievable. I'm a true believer now... and glad I can get off the damned trainer in the basement. Riding that was worse than Chinese water torture.
It's such a complete blast to be able to ride during ski season, when in the past that meant stowing the bike for five or six months.