
I am rather biased. I started with PVC windows 12 years ago in Australia. We had problems of windows and doors not opening/closing etc. I discovered that the rate of expansion for PVC in heat is huge, and this was the problem for large windows and for dark colours in any size… so I have stopped selling PVC for the last 7 years.
They work well in smaller sizes and in light colours or white.
IMO, if you can get a similar window for performance in aluminium, it will have far more rigidity.