Using the motion blur in the version 4.8 p1 with default settings i got problems with the models near the camera or attached to the camera.
Examples:
https://dl.dropboxusercontent.com/u/28070491/UE/Forums/MBProblemsA.png
https://dl.dropboxusercontent.com/u/28070491/UE/Forums/MBProblemsB.png
*Something to check the distance of the motion blur start or give more options about that.