Well I've had three more successful burns of the DVD9 from the "fixed" (magic-placebo-goggles-do-nothing-edition) ISO. They all work flawlessly on my PC.
Let's see if they still go to skip city on the other computers/players I test (again, sadly I have only four cheap players to test on and three computer setups) this afternoon...
Short of shelling out for another spindle of DL's and waiting a week for delivery, this is the best I'm going to get here I think.