chornedsnorkack,
I wish that I could fly in your operation, the vast majority of mine are runway or obstacle limited, in fact, I can't remember the last time that the full WAT limit was available to me. Even some apparently 'obstacle-free' departures are not so, an example, you have a 3000M runway Up-Sloping at 1.0%, you only need 2000M, and there's no trees, nothing beyond the runway. Airborne after 2000M with an engine failure at the WAT limit, can you out-climb the Up-Sloping runway during the 1st Segment?
On your second point, I'm not being defensive, but I did quote in the last line - ".....the best gradient speed is SLIGHTLY below VMD (but not so much that you'd notice).". Because of thrust degredation with speed, the actual Best Gradient speed may be 10 knots or so below VMD, but as the Drag curve is 'bottoming out' at it's minima in this region, +/- 10 knots or so speed variation will have minimal effect upon achieved Climb Gradient - hence "not so much that you'd notice".
For the jet aircraft, the Net Thrust line hardly plummets like a Disneyland ride, that's more in line with what is expected of a propeller aircraft. The gradient of the Net Thrust line is actually quite shallow, and for general discussion purposes is usually taken as horizontal.
It's pretty hard to make a comparison in generic terms between Vmd AEO and Vmd OEI, as they present two entirely different Drag Curves, you cannot use the one curve for both instances. In the OEI situation, windmilling engine and offset rudder drag markedly modify the profile drag, yielding a 'new' drag curve with Vmd at a lower speed than for the AEO case. BGC speed may well be lower than for the AEO case, but this will depend on the type of aircraft.
A good discussion.
Regards,
Old Smokey