Sbarber -- Compared to most of the Receivers that Luxman put out during its time marketing in America, that series would have to rank near the bottom in overall desirability and performance. And, I'm almost certain you didn't pay much for it if you acquired it second hand since they go cheap on e-Bay.
Certainly, there is no question that it is a more than adequate Receiver and does fine in a bedroom system but it is certainly not representative of what Luxman is all about. If you love the sound of the Luxman you have now, I can't imagine how much more you'll love the sound of the more highly regarded (and, unfortunately, more valuable) models.
All of your Receivers are in the 45-55 watt range, so they simply don't have the dymanic power to deliver music at its very best. If you ever get a chance, get a 120 wpc Luxman R-1120. I'd love to hear what your ears would tell you then!
But, you sound happy with what you've got so it might not matter. Good luck!
-- Chris