Suggest you get hold of the policy doc and read it thoroughly before making a decision. Although the Porsche extended warranty at £725 sounds expensive, and it doesn't cover absolutely everything (eg door seals, body parts etc), it does cover a lot more expensive mechanical and electrical bits than most of the other warranties, doesn't have financial limits, and covers European geography not just UK, including (if I remember rightly) vehicle recovery, hotel bills etc. So if you plan to travel to Europe (which I do) you can take that into account as well, if you would normally buy that separately. I hate paying the bill but love the piece of mind. For example, I have so far had a dicky ignition switch and the horn has just stopped working - no hassle, no poking around, just get it fixed by OPC. Not sure what would happen if the engine blew up on the Nurburgring though!
Brian J