I use perspex on all mt cages, it is good for hinged doors, you just have to be careful drilling in the pilot holes for the screws as it cracks easily.
I have used it for silding doors( I wouldn't recommend this as perspex bends quite easy thus leaving gaps.
I only used perspex because I have a young child (Miss 3) and I didnt want glass used in case she smashed by banging on it.
I personnaly wont be using perspex again, even though it was cheaper than glass where I live as I had to get it frieghted to me, where as Perspex wa available from the local Hardware Store.
A sheet of Perspex 1200mm x 900mm x 4mm was about $45.00 I think glass was about double that plus frieght