HD3 UI true annoyances for me (from what I saw on Dave's video):
- the screen size and resolution and consequential no-scaling
- the frameless split screens (give it a cheap look , IMO)
- the vertical axes values being on the right
- the top channels/menu bar should be on the bottom
I leave all the engine analysis for the experts, but at the UI level, the MXO4 is much more polished than the HD3. It looks like KS tried to innovate but, IMO, this is an engineering instrument not a smartphone skin project. Much less if we consider that it's something that can cost ~20k€.