I just received my new 2" larger version and it is thicker than the stock.
Does the thicker shield come with new mounting screws? I ask because the stock mounting screws will crush a thicker shield. Maybe that's OK. The stock mounting screws do not crush the stock shield or a replacement shield of the same thickness at the mounting holes.
Here is a pic of the stock screw used to mount the windshield.
http://www.nt-owners.org/forums/attachment.php?attachmentid=2240&d=1311095254
The shield should be the same thickness as the height of the unthreaded portion of the screw.
If the shield thickness at the mounting hole is thinner than the height of the unthreaded portion of the screw, the shield will be loose when the screw is tightened. The screw is tight because the bottom of the shouldered section is tight against the bracket it screws in to, but the shield will be loose.
If the shield thickness at the mounting hole is thicker than the height of the unthreaded portion of the screw, the screw will be crushing the shield at the mounting hole as it is tightened. The bottom of the shouldered section will not have contacted the bracket in to which it is screwed. Tightening the screw will crush the shield more.
If the shield thickness at the mounting hole is nearly equal as the height of the unthreaded portion of the screw, the bottom of the screw's shoulder is tightened to the mounting bracket, the shield is just held snug as the bottom the screw head contacts the shield. The shield is not crushed if the screw tightened.
I would not accept a thinner shield. I would not accept a thicker shield unless CB provided either new mounting screws or guaranteed crushing the shield with stock screws is safe.