Interesting thread.
One aspect which has not been discussed is the superior audio quality of BD, particularly for opera, ballet etc.
Now the prices have dropped to reasonable levels BD is to be preferred. However if the oroginal video is HD, DVD comes through rather nicely if upscaled by iScan with the note that PAL is superior to NTSC.
Few BDs are bad but I do have quite a few DVDs in that category and I generally dislike compressed DD although DTS is sometimes bearable. Crazy to have expensive audio rigs and then pipe the DD rubbish through it!
John