Sun's style Ba Gua is often refered to as Eight Animals Ba Gua Zhang. I've seen it, and had the opportunity to learn the empty hand set from a friend of mine, but never took him up on the offer. I kinda have my hands full with Liang and Coiling Dragon style.
However, I will say that there are 'LOTS more spinal twistings in the set I saw than in traditional Cheng's style. Almost every technique has the practitioner swivling his hips and shoulders in a wide circle like a hula dancer. They also walk using a Taiji style step (ie heel to toe) rather than the muddy stepping I've grown accustomed to. It seemed to be a much shorter set than the Coiling Dragon, but longer than Cheng's Eight Mother Palms or Liang's Old Eight Palms.
Sifu Jerry Alan Johnson has a video out called Eight Animals Ba Gua if you wanna see it for yourself. My only complaint is that he never demonstrates the form himself, but instead has one of his students do it!
" You must use your Dan Tien, spine, ligaments, tendons, joints, muscles, and chi for power. Your whole body together, not seperate parts. If you don't, you are not practicing Ba Gua Chang, you are practicing Ba Gua Bullsh*t." - Master George Xu