On my Ricoh-labeled RICOHJPNR01 DVD+R discs, are labels stating: "Caution: this disc is compliant with the new standards for 1x-4x recording. Attempting to use this media with 2.4x DVD+R devices that do not support 4x recording may result in writing error, failures in data-retrieval or damage to the recorded data."
If I understand correctly, writing at 2.4x is fine, but only in a drive that also supports 4x? I guess so, but they could have worded is better for stupid non-english speakers like me...
Secondly, and more importantly, having studied the graphs posted in the Ricoh test thread, I am inconclusive about one thing that I cannot test myself (I don't have a Lite-On writer, but a NEC 1300A): does burning 4x media at a lower speeds, for example 2.4x, give better results, roughly the same, or - worse results?
For example, I know from cd-tests that my Plextor 4824 has a 'sweetspot' for CD-R discs, which is 16-32x for crappy media and 32-40x for proper discs. This produces least errors.