I have a Gahh top with glass window and German A5 material and love it. Mine was around $1500 installed and I would never go back to a lame plastic window again. The glass does make it
slightly more challenging to get into the engine bay but sheesh... the minor inconvenience once a year is outweighed 100 fold by the magnificent clear glass window that no longer requires a Boxster chop each time you open your top. I say go for it!