Anthony,
I know that Runco LJR-II was based onto Panasonic LX-900... as about the differences, I strongly suspect they were more than minor!
So, the Panasonic MUST be a good player, at least for its transport... surely it is one of the few smear-free laserdisc player around, but as I haven't seen any in person, I could not say it is "only" good or really good...
So, I'm awaiting your tests - and complete review - about your brand "old" Panasonic LX-900!