I live in San Diego, a few weeks ago I took my 1200GS with the stock (streety) Tourance Exp tires to Vegas.
There's a pass which gets to 4200 feet. It was raining and about 41 at sea level. I haven't biked there before so I wasn't as intimately aware of the pass altitude (cage isolates you).
I said to myself as it kept raining and the temps hit 36 that I won't have to worry about ice. It's raining too well.
EEEK next thing I know it's a blizzard it's 30 and I'm stuck in the rut of the car in front. Unlike the TKC80 shod CBR I didn't feel comfortable crossing the snow/slush boundaries. (It was like his video but blizzard too)
Pucker factor 100%. Bike and I did fine 4-6 miles of "please don't fall" at 30-40 mph. Biggest issue was cold. Body was layered up (I'd planned for 40) but the gloves were single layer and the heated grips were OK but not really enough. Top of glove was actually frozen.
Cracking the visor was the only way to avoid fogging but it was bitter bitter cold.
Anyway. Looking forward to running TKCs full time.
So it's doable. Just don't goose the throttle. Mind you a lot of more sensible folk on bikes had pulled off. But I didn't relish waiting 2 hours for a truck to drive me out. In 30 degree weather.