Speaking as someone who was not there, I think an 8-scene BI is the best way to go as well. That said, I'm all for experimentation (especially, when it doesn't work, I'm not the guinea pig

).
Though, I know that BI's are supposed to be Con-exclusive events (and I understand WHY they are and should remain so), I'd love to see "abridged" versions released for homeplay. For example, if you have an 8 Combat BI for XP/sweet rewards, have a 4 Combat "abridged" version for half combat/less cool rewards. While wanting to play these is one reason for this, I mostly suggest this for continuity's sake as many of the HP's lead into the BI and there is a risk of no pay-off for the Home Players with that storyline. Don't do anything as awesome as at an actual BI, but focus on the bare-bones plot-lines (make it back to the city, defend the walls, clear the city, final push). Kind of similar to the 3.x adventure (The Serpentine Path?).