Well, that's a little embarrassing.
I would think I would have run across the "Just Burn" phrase by now. Oh well, I don't feel too bad since it doesn't (according to Google) show up on the official LiteOn site, and the LiteOn page for the LTR-52246S simply states "Buffer underrun error free".
You are correct that SMART-BURN is not
the buffer underrun protection. It is the term LiteOn uses to describe the technology for adjusting burn speed, power, etc. to give best burn quality. I misunderstood your question and thought you were talking about the burn-quality-enhancing technologies such as SMART-BURN and BURN-Proof rather than buffer underrun prevention technologies. Sorry.
Anyway, that seems to clear things up. Thanks for the follow-up post. I predict you will have a LiteOn in your Memorex box for sure. (famous last words...