Thank you for your quick reaction ! All is as clean as can be, for sure.
I choosed the 411s because I knew I will probably need a dual drive, according to infos on my players (dvdrhelp.com), and had a Lite-On 40125S CD burner which will work perfectly (I did never think to update the firmware !).
I had my 411s for just a week, and both box, papers, drive and system told me that it was just truely a 411s, with FS02 firmware.
Only then I found CD-Freaks, and understand it won’t be easy… I bought supposed quality media (Ricoh,Verbatim, Ritek, Traxdata, both -R and +R).
I tried first the DVD+RW (Ricoh JPNW11), then the DVD+R (Ricoh JPNR01) given with the drive, at 4x with Nero 6.0023, and all was good, except that my Toshiba home players can not read them without modifying book type field, what I expected…
I used the Lite-On utility for flashing first to FS0B, burned on a Ritek G04 at 2x only (according to what I read here). Poor result : freezings at end of disk in Toshiba homer player and PC drives, including the 411s, and “no disk” message in versatile JVC home player. What I read in CD-Freaks and Lite-On site forums convinced me I was engaged in problems…
It was just time to call (november 13) and obtain the return of the drive at my reseller, and then buy a Pioneer 106 to live reasonably in peace.
As I now have two weeks to return it, the FS0F was ready on november 14, and I have CD-Freaks for help me (and I hope I can help someone else !), I will test it and hope will be convinced to keep my Lite-On : it has obviously many qualities, and this forum is one of them !
But let’s get rid of the defects.