On my system Nero 6 has many many problems.
I have 3 Lite On recorders, a Sony DVD / CD combo recorder and a Pioneer DVD ROM.
One problem is with multi sessions discs and multiple recorders. If you use Nero StartSmart with a multi session disc, Nero always defaults to the last recorder you used. So if you stick a multi session DVD disc in and you last used a Lite On CD recorder it won't find the session! There is no option on StartSmart to switch recorders.
2nd issue with multi session DVDs is that it takes a VERY long time for Nero to add the previous session. You wait for a long time - with no indication that anything is happening. There is no dialog box to say it is adding the session.
Multi session DVDs use a lot of resources, heavy CPU usage (luckily I have a lot of RAM & a quick processor).
My multiple recorders are on Promise IDE controller cards - Nero sometimes is unable to burn, and aborts the burn (after 5 - 6 minutes of trying). The log says "SCSI command aborted", however this doesn't happen all the time.
I also have Easy CD 6 installed - it burns CDs without any problems - no matter which drive I choose. The only downside is that it doesn't allow multiple burner recording.
Its the first time I've used Easy Cd in preference to Nero. Nero has too many problems and doesn't seem to have been fully tested before release.