It's at moments like this that you will test the rigor and robustness of your
Insurance policy!
Having said that and without repeating the other points I'd just add the following:
1. Porsche do not make windscreens. As far as I know (on the 996 anyway) the glass is supplied to Porsche by Saint Gobain - one of the largest glass manufacturers in the world (by volume).
2. If you have a Hobson's Choice as Terry faced with his £100 contribution towards a £700 replacement or an excess fee of £50-£75 you have to be prepared to accept a cheap generic substitute rather than a Saint Gobain fitment.
I had the same experience earlier this year when my wife's Micra neded a windscreen. The standard factory fit is Pilkington - the guys from the fast fit outfit brought cheap generic that I'd never heard of. I raised the matter with the depot manager demanding a like-for-like Pilkington fitment. He stated that what they had supplied is an equivalent standard to the factory fit Pilkington (kite marks, BSI etc.) and that they are under instruction from the
Insurance company to fit the cheapest alternative (another test of your
Insurance policy).
That being the case, and deploying my usual persuasive powers, I changed his position to return a day later and fit a Pilkington windscreen (I could tell you how I did it, but then I'd have to shoot you cos he said he'd lose his job if his boss found out he fitted a Pilkington glass when they get paid only the cost of the cheapest generic product). This practice is rife everywhere - doctors palm you off with the cheapest genrics made in the back-waters of some Republic of Ketanga whose manufacturing standards were extolled in the BMJ - Bolivian Medical Journal.
Back to this thread, I'd say you are probably stuck with whatever glass is supplied is going to be fitted. So you might like to supervise the task and preferably at their fast fit depot under cover. Iy may just be that you get a Saint Gobain product because generics are only interested in products with high volumes where their cheap prices make money through product turn - they may only fit a few thousand Porsche glasses in the UK per year but many thousands of voume car manufacturers such as Ford, Citroen, Renault, Nissan etc.
Hope you get a solution that is acceptable to you.
(By the way, my
Insurance does not limit me to fast-fit guys, I can have it doen at OPC in this instance but excess goes up from £75 to £150. Not bad for a £700 glass fitment that will be sub-contracted out but watched like a hawk by OPC - becasue in such a situation the contract is between me and OPC as I have elceted to delcine the insurers choice and picked my own repairer.