Hi Chuck,
I am not seeing your point regarding Blue Line, if you are taking of from a 2000 metre runway in say a C310 or a C404, why shouldn't blue line and insufficient runway be the go / no go decision ( brakes, positive rate, gear up ) ?, then Blue Line plus ten in the fourth segment climb ?.
1.2 Vs is certainly relevant when ( or as per POH ) operating from a short field where performance is a huge issue, but if performance is not the primary consideration, control will certainly then become the primary concern, i.e Blue Line ASAP after take off .
Same logic for landing ?.