I'm not sure we were quite double their size. In July 2010, Digg claimed to have 200M pageviews[0] and we had 279M[1]. So I think we were more like 40% bigger in terms of pageviews, which Chris's post from the time[2] seems to confirm. Though we were undercounting a bit[3], so it was probably more like 55% or 60%.
And when it comes to uniques, my memory's pretty foggy, so please correct me if I'm wrong, but I think Digg actually had more than we did at that point.
That said, you're absolutely correct that we were far from struggling, except in terms of getting approval from Conde Nast to buy more AWS power, or to hire, or to get any support whatsoever from their ad sales team.
[0] http://thenextweb.com/socialmedia/2010/08/28/kevin-rose-resp...
[1] https://github.com/drunken-economist/reddit-10-year-data/blo...
[2] https://www.reddit.com/r/blog/comments/d8d1f/dear_entire_mai...