the category system is
Insurance only, and has no baring on anything else, the same rules apply to buying as you would any other car, inspect the thing, and check it over, then make your mind up as to purchase.
obviously a cat car has a lower value because of the kudos attached.
please remember there are thousands of heavy accident repared cars out there, hundreds of 911's that have not been subject to an
Insurance claim, therefore have no cat attached,
it all depends on the quality of repair and/or condition.
a lot of porsches that suffer damage on a track etc, are not recorded, then repaired, and sold as normal, so do all your inspections on ANY car as thorough as you can.
catogory cars are no problem at all, as long as they have been repaired properly, and you take into account the difference the stigma and label will have on resale (its just that...a label)
i recently bought a flood damaged 997 turbo PDK (60 plate)it suffered water ingress up to the seat bases, and was given a cat B status, because of the risk of safety wiring such as air bags, pre tensioners etc failing due to rusting.
the car was immaculate pre flood with very low milage, i bought it for £40k under its book price........ it only cost £5k to replace 2 ECU'S seats, carpets, and loom various other small bits....then an SVA test to check the cars "repair" then a normal MOT and a re issued V5.
car was then as new, but it carries the stigma or label of a heavily damaged car (not)
so its not always as people think, sometimes its just a fiscal move, sometimes it can be very bad damage, you have to check and double check,.
do not be put off by labels, its the car and the cars repair/history that is paramount, not some paperwork that might be bogus in its self.
as mentioned if your thinking of keeping then they are very good value, if your purely into money, then its not for you.
i bet there are some badly repaired porches out there, that are not recorded, and plenty of lovely straight ones that are.
whats in a name.....