I am really curious how BGFX will affect input-lag and will wait for new tests regarding this. BGFX can be a good thing, as it is a cross-platform API, so i assume official MAME is targeting tablets and smartphones too in the near future (just like Retroarch). Sadly i still dont see multi-pass shader support. Sure the JSON files will help converting existing shaders easily, but without multi-pass, i will not invest any afford to do this.
Regarding ddraw, it was nice to see that the MAME dev team at least try to port the integer-scaling to directx. I am more worried about the drop to not support CRTs anymore in general. God bless Calamity and i honor him for his afford to keep the CRT community satisfied. Sad thing is, that he can only keep up the different video modes to support CRTs, but not the drivers itself.
What does this mean? It means that the devs are already starting to optimize the drivers for LCDs, which in turn can falsify the result what we see on our loved CRTs. Take Atari 2600 for example and start any game with high motion in it and then pause it and examine the screen. You will explore the blending of frames, which the devs did to avoid flicker on a LCD. This frame-blending did not exist on real hardware.
Here is a example of HERO and now notice the blending on the hero-figure:

This will affect the game-display on a CRT and is a thing we can not avoid in the future. I was upset that the devs really think, that the CRT community is just 1% of the whole MAME community or their general thoughts about CRT. I am even more wondering what this has to do with accuracy

We really need to cherish Calamity, as he is the only person, who defended the CRT community in the lately discussions, we had with the devs.