One advantage is that it could save you having to create an additional index (in addition to surrogate key index) on the child fk columns if these are ever used in select criteria (which they often are as you typically want children that match some criteria for some particular parent).

Pushing keys down into child tables is a real help if you need to query something way down a hierachy of parent child tables when the key of the grandparent/great grand parent table is needed in the query as it saves having to join thru all the intermediate parent tables. However wide keys effect the efficiency of the index. I've seen dramatic improvements on queries with 5 tables in parent-child configuration being adapted FROM surrogate keys to cascaded primary keys where the final child table had ~10 million rows. The key was numeric and only one column was introduced per level. If the key columns are "wide" (long character strings etc.) then this will tip the balance away from cascaded keys.

Andy