Excellent stuff! Wish I had this info when I did mine 25 years ago. I have a 0.125" windshield which is starting to craze around a couple of the forward fasteners so I need to replace. I will go with a 0.1875" replacement. Been thinking of how to build the aft trim strip(fairing) into the plexiglas. Was thinking of routing 1/16" deep and laying in a fiberglass trim strip so finished trim strip would be flush with the original thickness and extend aft to allow canopy to fit under when closed. No draggy lip! Any one done anything like that?
Also the fact you are reducing the thickness of the glass in that area 
Especially since it attaches to the roll bar there. 
I used a 90 degree die grinder with a 1/16" cutoff disc at a speed just fast enough to cut and not so fast as to melt. The 90 degree die grinder I found gave me great control of the cutting. Most of the time it took several passes to make the final cut. All my attach holes were drill initally with a #40 drill (slow speed with a back up block behind the glass), followed by a UniBit drill. The Unitbit drill made a smooth hole and deburred the edges. A 7.5 volt drill was used at about 500 RPM. 
No cracks !