I have an NEC ND-2500A (using Herrie’s patched firmware to allow writing to dual layer media and bitsetting).
I also have a Sony DW-U18A (using codeguy’s patched firmware to make it an SOHW-832S and allow writing to dual layer media).
I’ve had the Sony drive for less time, but thus far, I prefer the NEC drive.
The NEC drive has great write quality on all types of media, DVD+R and DVD-R. While I haven’t used the Sony drive to burn much (I got it to run Kprobe and Disc Quality check in CDSpeed), the times that I have burned with it, I was surprised at how much the buffer fluctuated and how when it did, the disc came out unreadable. Unlike my NEC drive where I can write at 8x and still do other things on my computer (like play in Photoshop), trying that with the Sony drive ended in coasters. And from reports I’ve read on this forum, LiteOn drives can be iffy with some DVD-R media.
I’ve burned one dual layer disc in the NEC drive and it came out great. No problems with the media or the burn. Haven’t tried it with the Sony drive yet.
I’ve been very happy with the NEC drive, and at the price its going for, I don’t think anyone would be disappointed.
That said, the LiteOn drive has some advantages: bitsetting in the official firmware (you need a hacked firmware for the NEC to do bitsetting), the ability to do Kprobe/Disc Quality scans (a feature most people will not need), and its in a retail package so warranty is easier to deal with, if needed.
Both drives have a talented community of users, and firmware patchers, behind them.
Knowing what I know, and being comfortable with using a patched firmware, if I had to buy a new drive right now, I would buy an NEC ND-2510A.