I got a promotional email from LiteLok about this with a £5 discount as a pre-existing X3 owner. I jumped at it as although the lock is awesome, it is a hefty lump to carry, particularly for short journeys where a pannier would not be needed except to carry the lock. I fitted it in about 5 minutes - there is plenty of adjustment to fit the majority of bike frames and it dealt with my bikes weirdly tapered top tube fine.
Unlike so many frame mounts for bigger D-Locks this ones doesn't rattle or move in the slightest - apart from the additional 2kg+ on the frame, you wouldn't know it was there until you needed it. I'm dead happy with this - it makes lugging the lock around so much easier.