I think some Hemi's of that era had problems dropping valve seats. However I have a 2007 Magnum R/T with 170,000 and have not had the problem.
Perhaps someone else here will no more.
The folks that I know that have had Durango's over the years have liked them.
Dropped valve seats are usually fallout from running an engine low on coolant, coupled with an insert material spec problem..
What happens is that if the engine is low on coolant, it may run fine and show no overt signs of overheating because as long as the water pump is turning, the cylinder heads will be filled with coolant.
As soon as the engine is stopped and the water pump stops turning, the coolant drops below the cylinder head deck level, and the metal temperature in the valve bridge area skyrockets. If the valve bridge doesn’t eventually crack, the high temperatures may, depending on the insert material spec cause the inserts to fail in compressive yield. Essentially the hoop stresses induced exceed the yield stress capabilities of the insert, they collapse, loose the press fit in the cylinder head, and drop when the engine is restarted.
Insert material spec changes cam eliminate or at least mitigate this failure mode.
Typical engine design and development should include the FEA analysis and dyno tests to eliminate this failure.
High mileage doesn’t cause the failure, it’s the lack of cooling system maintenance and subsequent overheating on shutdown that often is a byproduct of high mileage.