I had not thought about directional vs twin....hmm.
Jumping for me is up to medium sized park jumps, 10-20' rock drops and my favorite is carrying some good speed and jumping off of the lip made by the roads. I'm not very good...I mostly do straight jumps with some grabs or a shifty and a few 180s. I prefer to start switch when jumping a 180 though. I will do any of the 4 180s (only on small jumps). I do some straight jumps switch...just smaller stuff.
My crashes vary from too much weight forward or back to catching an edge. Most of my crashes result from a forward or back weight bias though...in those scenarios, I skid out after doing some crazy ballet type spin upon landing. When I catch an edge, I see a few stars and talk funny for a while