[cthalupa]

>The point is that if my application will actually go down anyway if the WAN craps out, then really, I don't actually need P.

Can you guarantee no further modification to the data in the database occurs when the WAN craps out? What happens to in flight requests, batch/scheduled jobs, etc.? There's no situation where your application continues modifying the contents of the database even when there's no WAN link?

I've seen very few real world services where there is a 0% chance of data changing just because the application servers can no longer talk with clients but can still talk with the database. What happens when those databases try to rejoin the cluster and their data is now inconsistent, if you did not take into account partition tolerance?