DDP files for DVD replication

Are people exporting DDP files from Encore to send to replication houses? I don't see much recent discussion on this?

Encore will export DDP files to a hard-drive. Can these then just be copied onto a DVD-R as data?

how to check the DDP file DVD before sending it off to have 1000 copies replicated? 

Any down side? It sounds like a good system (?)

Thanks for any tips or discussion -