^^^
not familiar with the recent dvdo offerings, but for the edge i was a beta tester for, nothing really (that doesn't mean it's not useful for calibrating)...
as far as the lumagen... not necessarily on the deinterlacing side (although the deinterlacing on the lumagen definitely does not suck) but on the scaling side, yes... on an appropriately sized screen at an appropriate distance, the "no ring" scaling algorithms produce a positive difference "worth" spending for, especially if you are of a mind to use the calibration tools that also come with the unit... the difference is VERY evident on my 110" screen, but not nearly as much so on my 60" display...
deinterlacing was what seperated the men from the boys for a long time... however, virtually all chips use some type of adaptive deinterlacing techniques now, and that has significantly closed the gap...