Daily Kos uses Scoop but is planning a move to a new ruby-on-rails engine that they're writing themselves. The diaries are a good feature for a community where you want to encourage the readers to be actively involved, but I think the quality of the diaries is likely to be lower than the current quality of posts on OB. The threaded discussion could be really valuable, however, and with good editing the front page could be awesome. But you'll have to find good editors if you haven't the time for it yourself.
billswift: I'll accept that more driving means more hours driving in those dangerous situations. In that case, it seems that 9/11 actually increased the safety of driving, if measured per mile. At least, the number of accidents only went mildly up, but the number of miles went up dramatically.