Yes, but from an application perspective your database will be left in an inconsistent state. The next morning the ops guys will have to call the dev guys to "repair" the database by hand.
Truth is ScalienDB runs in W=3 mode at about the speed MongoDB in W=1 mode, so this is not a trade-off that customers have to make.
Not yet. ScalienDB uses synchronous replication which works only works inside the datacenter. Across datacenters is a completely different use-case coming in 2012.
Truth is ScalienDB runs in W=3 mode at about the speed MongoDB in W=1 mode, so this is not a trade-off that customers have to make.