My 72x required RMA about a year ago and the returned product with updated firmware runs well, except for being unable to read some CD-Rs on some media. I use it whenever I make a new machine that requires the clean installation of software. For that purpose it is unbeatable: very fast, relatively quiet too, but has limitations as described in this thread. Once all my OS and applications are loaded, then I switch out the Kenwood for an Afreey 56x (also fast, but loud).
I also got the Dell Lite-On DVD deal this month and will switch out the Kenwood for this 16x/40x DVD this time. Waiting for my next board-chip combo to arrive this week to finish off the newest machine (1.6a overclocked to a sizzle).