Update time!
So, DPS work has progressed generally well, although there are still lots of open issues. I was sort of forced into increasing the MFD resolution to 1024x1024, so that the (few) display coordinates I have could be used without conversion, and certainly rounding, which would result in things not lining up as they should. Performance doesn't seem to have degraded much, so I'm sticking with it.
Here is the current state:

The menu, as well as the MEDS displays, are still in need of a "review" of pens and font sizes, as I've just multiplied everything by 2. Only the DPS display is +/- done. In this one, the main issue is the font: D3D9 has some extra bits showing in some chars (right-pointing arrow on alpha scale), and no function can't rotate my custom font. Plus, some chars are still not finished, and I might have to resize the whole font a bit. And also, I had to move the first 32 chars of the font to other locations, as them being visible isn't "certain", and convert the indexes so the GPC still kept the original char table.
On the other hand, the IDP now receives the background part of the display once and keeps it in memory, and the GPC only sends the dynamic parts 2 times per second, which means MFD redraw requests no longer have to go into to the GPC, making it a bit more independent from Orbiter Still, more work is needed on the GPC: internal display management, DK bus commander management, BFS displays, IDP clock update.
Another great source of work is the A/E PFD. With the bump up to 1024, some tapes no longer work, as their size is just too large, so I need to rework all that to draw in real-time only the part that is needed... fun.

I also need to finish work on the IDP "crew station" management, to decide which data is used on which MDU.
All of this work will slow down as I'll now turn my attention to having a version ready for Orbiter 2024, and maybe a final version for 2016 (it depends on which is faster: SSV or Orbiter). I can't tell what new features it will have, as I honestly haven't decided.