The 4800 is discontinued, hence it's reduced price. The 4800 uses the Genesis deinterlacer vs the 1815 using the Faroudja DCDI chips, the latter generally accepted to produce superior video. The 4800 is/was able to play DVD-A whereas the 1815 does not. The 4800 has a larger buffer (if I recall correctly) to reduce layer change time.
I guess they both have their good and not so good points. I've never used a 4800 but did own an 1815 for a couple of weeks. The picture was excellent but the layer change bothered me. It's a little ??quirkey?? in the way the carousal function works (at least mine was) and overall just felt a little on the cheap side....noisey, though not bad and flimsy in some respects. Anyway, I traded it back towards a 2900 and am more than satisfied with that unit.
Mort
