DL media, can't say I can help you. I have only burned like 3 DL disks in my life, and only 1 of those worked. I have no idea if that was due to the source or the media though. I was trying to back up my OS X install disks.
I like Memorex for DVD+Rs though (and DVD+R is the way you want to go).
My NEC DVD burner won't even recognize my brand new Sony single layer DVD-Rs. C'mon it's year 2010 and we are still seeing crap like that? This illustrates why nobody deals with optical media anymore.
As with many other shrinkwraps, Sony doesn't make their own DVD media. Years ago, they used to be OK, especially if the label stated "Made in Japan" (aka TY). Dunno where they get their discs today, tho'As for Sony media - can't say that I have any great positive or negative things to say about it.
There's a bit of a misconception here...Verbatim's Life and Value lines are regarded as garbage. In addition, Verbatim also switches suppliers like many other vendors: there have been numerous product listings on newegg over the years where a specific SKU will get nothing but praise for months (made in UAE or whatever) and then suddenly get hammered by reviewers (made in India, etc). So it can be a crapshoot.I personally prefer Verbatim media. Next to Taiyo Yuden DVDs, they are hands down the most reliable quality.