John you make some good points. Some where around here I have formula for the optimum bank angle (optimum for control and climb). Rather than play with numbers, I found a yaw string worked best for finding this angle.
The only reason 5 degrees of bank exist is becouse of the FAA. You can continue to reduce Vmc by banking steeper. The FAA wanted establish a level playing field amoung the manufactures, thus the limit. You can however, continue to bank into the operating engine right up to the point you stall the rudder (yes, stall the rudder) then the airplane spins like a top!!! (you will be well beyond 5 degrees of bank but at what bank angle this rudder stall occurs at is anybodys guess)
An accidnet investagator friend of mine pointed out something from his experiance. Most loss of control accidents resulting from a engine failure on take off occured at a speed above Vmc. He beleaves the pilots where attempting to steer the airplane with the ailirons and very little rudder and one wing stalled before the other.
Two other points on Vyse. Vyse also varies with weight as well as with altitude. At sea level "blue line" might be close enough but at high altitude it will not. Same with weight Blue line is at gross weight. The indicated airspeed for Vyse decreases with a decrease in weight. This improves the rate of climb as well as the climb ratio. I know that if a take off is attmepted with a high and heavy condition, climb performance will be minimal to begin with, so flying the proper airspeed may make the differance of making it or not. (Again, I try to avoid this situation)
Another place to use Vyse is in a single engine drift down situation. Flying the proper speed here will increase the "glide" ratio and you will level off at a higher altitude.
I'm always thinking that damn engine is going to go south on me. The odds are 50/50.
No airplane has enough power unless it can accelerate going vertical!!!