Spent very little time w earlier versions of the APD, or Babs holistically, due to almost instant arm discomfort.......
2012 PD w Active Cortex was the game-changer for me----
Demoed bc ridiculous cosmetics & could not believe the improved/ dampened feel- ultimately just not right fit, but no discomfort issues.....
2013 APD def IS right fit for me, & stiffness has not been an issue at all,,,,,
I string as well, so tried multiple setups just bc I can, and happy w multiple full poly configs <play poly/poly hybrids pretty much exclusively>........
Only setup that has not worked for me is either VS or soft multi mains, bc too powerful w overly dampened feel, resulting in poor control......
Favorite to date is Tour Bite 1.15 Mains/ Big Ace Micro 1.15 Crosses @ 57.5/56.5 w leather grip + Supergrap o/g <6pts HL / 11.7oz static>
This setup has played phenomenal for me----
HUGE controlled power/ spin w incredible comfort & feel.... prefer playing w/out dampener w this setup bc very minimal difference
Yonex Ezone AI 98 ~ Full Poly Hybrids
2012 Gamma 5003 w/ Wise