I'm not so concerned about the environmental or cost arguments, it's simply how long the data will actually last on each medium.

I plan to supply both a DVD, which plays a SD slideshow of images set to music in a DVD player, and a USB stick containing all the full res JPGs. The idea behind this is to remove some confusion me supplying 2 DVDs is causing, even with clear labelling some clients get confused between the 2 for some reason, so my thinking was to remove this while providing more security for the "digital negatives".

Cheers

Cris