Update: the answer (for me personally) turned out to be 1.65
Mount Washington: 01:32:08
Alpe du Zwift (PR): 00:55:52
The Mt Washington Hillclimb was amazing. No harder or easier than what I’d imagined it would be - just an almost unrelenting 12%-15% hill from start to finish. The few times where it dipped into single-digits were short, few, and far between. Visibility for the last mile was essentially nil thanks to dense fog/cloud cover. Loved every minute of it!