Major Description
ContentMirrorStoreStrategy has a bit of code which multiples the cost of a "is not null" query by 10. This code was added in r1501746, but there's nothing in the related JIRA (OAK-894) which mentions this change.
It appears to me that this multiplier should only take effect if the maximum node count has been reached. Otherwise, this code vastly overstates the cost of a query.
In a recent test, a property on 45 nodes generated a cost of 452.