From what I learned while beta testing OPPO's 983H (which uses an Anchor Bay solution for the video processing), supporting resolutions other than 720p, 1080i, and 1080p gets into some nasty issues with display timing that are very difficult to accommodate. Because there isn't a single standardized resolution, refresh rate, and such for "768p" (to name on example), it's messy to try to support output resolutions like these. I think that's part of the reason that we typically only see those standard resolutions supported.

Of course, I could be wrong, and it would certainly be cool to see support for that sort of control from Outlaw, but what I heard from OPPO (who were using chips pulled directly from a standalone video scaler) left me thinking that it's not something likely to show up outside of a $1,000+ video scaler component...