If I was buying a used 996 Cab, I'd prefer a genuine Porsche top or at least one made with OEM style materials. How long are you keeping the car?
I had similar questions when my Boxster top needed replacement (simultaneously with me needing to sell the car) In the end, I sold the car with the bad top and let the next owner decide
I would think that replacement is DIY able, just comes down to having the time, tools and
patience to do it yourself.