Scans look great, but be aware that P9 firmware has data integrity and playback issues with CMC (very popular) and Daxon (benq, sony) medias. These issues have been fixed in T9.
So, if you're shipping this drive out/have already shipped this drive out with P9, advise the relatives of good sources to purchase TY, Prodisc, and MCC +R medias.
Otherwise, you may wish to switch to T9 in case your relatives shop at any retail store where they are very likely to pick up some CMC (disguised under 23 different brands/packaging, all on sale) and then call you on the phone for each and every annoying coaster.
While the scanning performance of T9 is marginally lesser, playback and data integrity have improved greatly for most medias.
You may also wish to advise the relatives to use 12x speeds whenever available because 16x reduces quality and saves only about 20 seconds.
Hopefully, this is a retail drive and includes the near-bulletproof RecordNow. If not, you may wish to provide DVDshrink+DVDdecryptor (advise burning with Decryptor) for their backup needs.
Hey, the good news is that BenQ's quality product is easy to support because it usually works much better than average for a DVD writer.
edit: I re-read your original post. The RPC1 can generate support issue headaches and additional trips to cover the support needs of your relatives (true of anybody's relatives). Use only retail firmwares.