DoB, what tires were you on when you encountered the 1/2 of snow? What does it feel like going over similar snow and ice conditions with studded tires? I'm also wondering if the 700x38 Marathons I have on now are sufficient or whether I wouldn't be better off with 'winter tires.'
I was riding Panaracer Pasela 700-32's. On ice they have zero traction. The first time I fell was on a concrete road crossing an expansion joint that was parallel with my path. The tires lacked the traction to climb the 1/8" bump in the concrete and the road just dragged the bike out from under me.
My normal winter bike is a 26" hybrid. I run Nokian Mount and Ground studded tires. They ran me about $40 each. I run that bike on sheet ice and thin snow at full speed no problem. Traction on the studs is absolute on ice. They dig in and the bike can be turned / stopped no sweat.
Added bouns, when turning on the studs on dry pavement a delicious buzz runs up the seat post.