WOW, that is a lot of disc, I’m strictly authoring so no duplication like that. Not sure if I have made 4000 disc in my 10 years of authoring.
But I think the important thing is the top brands AND correct authoring practices can produce extremely high compatibility and play rates. Paying a little less to get sub par DVD-Rs gets eaten up with one FedEx shipment to replace a bad proof or master.
I would add TDK and Sony to the brands to stay away from.