notice your character tends to hover on jagged area's of the map and is flat on the ground where no such jagged ground exists? that's whats causing the annoying jitter it has nothing to do with the camera or slopes although its worse on slopes because for some odd reason the character model takes a few Milliseconds to connect to the ground while going down slopes.

PC Character models also seem to be abstracted from the world, while NPC Models seem to fit right in.