Convertible rear window... plastic or glass?

I been told that where the early verts had very large rear glasses ( like my 67 fish ), unzipping the rear glass isn't absolutly required when its a plastic window but...
If its a hard glass you do have to unzip that recal every time you lower the top.
The smaller generic hard glass that comes with reproduction tops may be a better choice.

My 67 Dart has Chrysler logo glass in it, I HAVE NEVER UNZIPPED IT, except when I removed the top from the car in disassembly

had a 67 Barracuda convertible with glass, didn't unzip it either, not sure if it had factory glass or aftermarket, but looked very close to the one in the Dart