I think there was a thread or article on AH that touted the advantages of the Darbee upgrade.
Simply put, I have no reason to doubt the Marantz, other than there is absolutely no information, much less marketing, to be found about how superb the video playback is on the Marantz. It really seems like a hole in one for them to add extra SKU's for people already decided on a pre/pro or AVR. "Look, they match!"
Just a natural born skeptic! And I speak for the BDP-93, I've tried it on multiple TVs and it alone is a night and day difference. The 103 is the current model, probably a few upgrades. And then the 103D just adds to it.