Unfortunately, it is not necessarily easy to replace... The zippered windows do not zip out, as they are attached (sewn) at the bottom...I see that ezsofttops.com sells tops with a zippered rear window. This seems like a great feature, if the window split or became cloudy it would be very easy to replace.
I've never had a zippered top, but I did have a Spider with no window. It was really nice, and that's why I consider myself "experienced" in this topic... From asking 2 people who have had zippered windows on their Spiders, I understand that they don't leak, and there not any noisier than the regular top.How well do the zippered windows seal? I've thought about one of those for those very hot sunny southern days ('69 no AC) where you want the sun off but you do want some better ventilation.