Emailed Shift about the jeans because I too what some butt protection. Here's what they said:
"The Torque denim has protection in the knees and seat area. This is done with three layers of material sewn together, the (1)outshell of denim, (2) a layer of Kevlar/Nylon blend weave, (3) a layer of thin soft poplin for comfort against the skin (the kevlar has a little bit of a rough finish, so the poplin is mainly there for comfort). It is not removable and mainly helps protect against abrasion, but not really impact.
Shift Racing Team"
Might order them this week. Still debating whether I want leather. But if I do get them I'll give a review.