Congrats, your data is great! Now run that super-efficient 2.5 foot chord case (260 HP) at 80 knots and see what its stall behavior is. This proves my point, I think. The low speed of Vne is a necessary tradeoff against the hover efficiency.
Also, don't think the 2.5 foot chord is better than the 1 foot chord, until you run the total system weight for it, and a thinner chord blade set. My guess is that the helo with 2.5 foot case has an empty weight of one or two hunderd pounds more than the 1 foot case.