Shen & Zhao's sbs spins are always their nemesis. I really love love them, but everytime I saw the posture of shen's sit spin, I was cringing. Anyway, which pair does not have weakness?
I guess the bad sbs spins you see these days have to do with new rules. There are just too many changes of feet, positions. I watched some clips in 2000-2001. Even Shen&Zhao had great unison in their spin at that time since they did not need to do spins that they were awkward with.
D&D's spins are truly amazing considering the difficulty. They are fast, centered and close together.
All the other pairs are pretty bad. The German pair S&S tend to lose unison completely at the end since they spin too fast.