Ta Alex.
Don't have any graphs available so I'll have to think on it. My initial thoughts re the BN2 was that the curves were particularly 'steep' ie compressed in the x (speed) axis, resulting in Vx & Vy (AEO & 1 inop) to be very close, compared to other aircraft. Still seems odd to me though, especially considering the large performance reserve (AEO)...
For your text discrepancy, what speed range are those graphs for? Perhaps the curve's shapes are an artifact of allowing/not allowing for compressibility effects?