I watched one of Cruiser Customizing's videos about windshields. It was impressive, and basically reached the same conclusions Stevea reached. The "polycarbonate vs. the acrylic" issue was a deal breaker for Memphis Shades (for me). You can beat the polycarbonate (literally) with a hammer and it will stand up without a scratch. You can also drill holes in it to attach mountings, etc. and the holes will not, apparently, weaken the "glass".
On a personal level, my 07 VStar 1100 Classic had the Switchblade (pop-off) windshield when I bought it, with the ability to mount or dismount in 1 quick movement; what a wonderful feature when you are riding in town a lot, but hit the long road regularly. When I "travel to ride" I can throw the W/S in my bike-trailer toolbox (a pickup bed toolbox) and have the W/S on when I need it, or pop it off in a second when I want to feel the wind on my next ride (picture riding the "Tail of the Dragon" without the windshield, but having it on when getting there from 900 miles away).