"Shaun Eli" wrote in message
oups.com...
The fill is ten feet deep-- remember, it's a driveway that sloped from
the street to under the house-- and I have no way of knowing what was
put there.

With that much unknown fill you really don't know WHEN it will finish
settling. (Even reasonably well placed fill can settle for a year or two).

Were I you, I would put go for the cheap job and be ready to add another
layer IF things settle more. With 10' of "unknown" just replacing the top
6" will not make much difference.