I tested LDW-411S for an hour or two. I got a sample drive from a South Korean distributor last week as expected.
Writing to Ricoh 4x DVD+R was easy. Writing to Princo 2x DVD-RW took a bit longer naturally but the read quality told by Nero CD-DVD Speed was poor at the last 100MB.
The drive failed to write to two 4x DVD-R media I have which must be because of some problem on my system since they are already known to work well with LDW-411S.