Nae Luck Dave and Eck.
The A90 south was close to impassible between Stonehaven and Laurencekirk at 06:00, and as you discovered, there were some fairly big snowstorms further south. Dundee was in whiteout as I passed through. There were a few cars off-the-road through the road-works contraflow: they'd taked the contra-flow lane-change shimmy too fast and taken out the row of cones and landed up on the grassy bank.
The drive home was more sane.
ETA: I also had a sneaky second breakfast, at Kinross services. I got some odd looks, still in my cycling kit.
Although we DNF'd it early at the North side of the bridge, we managed one of the best pieces of indecision ever. We did about 4 partial repeats of the bridge in a yes-we-will / no-we-wont flap. Still, it made up the majority of our km for the day.
Best of luck to anyone who's still out.