Quote: "well the best rate of climb is only that. most hight to distance"
This is actually the definition for best angle of climb; best rate is height per unit time.
Also the reference to Vtoss is a little misleading as it refers to multi-engined aircraft where minimum performance guarantees have to be given in the event of a critical power unit failure, that don't necessarily come from Vy.
I am suprised there is such a large difference in speeds, what exactly does 'best autorotational speed' mean? Is it a compromise between minimum rate of descent, flare characteristics and range? Normally min RoD and best RoC speeds are very similar (TAS). Is it a function of pressure error (IAS)?
I suppose that what ever the reason, you are better at higher speed as it gives you more options in the event of engine failure, and is probably more comfortable for the pax and you make better progress en-route.