If you look here:
you’ll see that there is more than meets the eye when it comes to PX712A.
I’ve had two bad drives, suffering both of the same symptoms, and even my third hand picked drive, only works “well” with “most” media … FW 1.04 seems to me worse than FW1.03 … and I’m waiting - as many others who have significantly worse drives than me - for Plextor to release their firmware upgrade at the end of the month, which allegedly will fix all these problems!
My advice: currently it is a lottery … if you can wait until at the end of the month, just wait and see if this magic FW will cure these problems for all those people affected … if it does, then go for it, otherwise just stay with your 708 which works great. Based on my experience and what I’ve read in various forums here and at cdrinfo.com, I would play safe if I were you!
712 is already absolete anyway, you can buy brand new released Pioneer 108 or NEC 3500 drives for less than the current price of a 712, and they are 16x drives with 4x DL!!!