Go to the standard page and see how many people are complaining about stress cracks. I couldn't find any. New shell, new motors, maybe a combo of both but they seem to be holding up. I didn't notice any difference at all in performance between the too. Only thing I thought when I first got my p3a was that it actually seemed less noisy than the p3s with the new motors
I asked the same question on the P3S page. No one had any issues.
P3S shells have the 'pointy tabs' but no X reinforcements.
So there could be 4 different shells.
- flat motor tabs, no X reinforcement (Adv and Pro)
- flat motor tabs, low profile X reinforcement (Adv and Pro)
- pointy motor tabs, stiffen X reinforcement (Adv and Pro)
- pointy motor tabs, no X reinforcement (Standard - no one has proof that a Standard shell is transferable to the Pro/Adv).