Hmm... User-created diggs (like we have on reddit, but better articulated & designed - I say this as the closest thing reddit had to a designer, I'm no designer). I have no idea about headcount, so I won't speculate there, only to say that reddit's ratio of 1 non tech for every 5 technical worked well for us.
And i'd make that digg mascot more prominent, maybe change it around for holidays, too.
User-created sections like the subreddits on reddit would be cool. In fact I think the subreddits are what I prefer about reddit over digg. I mainly go to the programming subreddit and sometimes I am deceived into thinking that all of reddit is about programming because it in itself is a large community.
But apart from the programming subreddit I go to the AMA section from time to time and that has allowed me to really grasp the beauty of the subreddit system. It allows each subreddit to develop it's own personality in that it's not just the topics that change as is the case with a category system but the feel and concept of the community changes as well and it offers a unique experience to learn and interact.
This is also my understanding from people in the know. Jay Adelson was removed from the company and most of the codebase for Digg v4, that was supposed to be launching sometime soon, was scrapped and Kevin took over the direction of the company again.