I have to say that I'm not surprised that you found those racquets to play differently. When you are trying to determine how a racquet feels in play from specifications on paper (like you are doing in your test), generally, you consider swing weight and stiffness as secondary to many other specs. Specs that are better indictor of how a racquet feels are headsize, beam width and balance.
The softness is probably due to the thin beam and smaller headsize. I'm just postulating here but the APD has woofer grommets which will create more power in the string bed and that equals less flex/ torque of the racquet. And the general rule is that thinner beams have more flexability that thicker ones. So there might be something about the SP that makes it test at 70 (possibly the D3O in the throat) but it doesn't acutally play that way.
Wilson 2011 blx 95 18x20- polystar energy 18g @50lbs