I have no electronics experience so I cannot shoot any direct comparisons between MD and the Trigger IO on a hardware scale. Obviously the IO uses much smaller PCB components in general. But everyone is correct, it looks a lot more "complicated" in general. Tons of traces everywhere, lots of little components everywhere.
I think the most interesting part of the board is the stacked TRS jacks, on/off, etc. directly mounted to the main PCB. And the stacked input jacks are on there rock solid. I tried briefly to pry to top one off the bottom one to see if there was some identifying label on the jack, and to see what the intermediary bridge piece was between the stacked jacks. But regardless it seems like a great way to mount the jacks to the PCB. And the fact they stack so tightly would help facilitate squeezing more input jacks into a smaller chassis much easier. I probably spent as much time stripping the IDE cable and soldering it to my input jacks as I did populating the entire V2.8 PCB with components.

On the flip side of all of the jacks/etc. were directly on the board it would limit your chassis selection, and then you'd require some sort of printable rear-panel template to accurate drill out the necessary holes properly. Though that'd be a time/problem saver I'd think.
But I still think it'd be an excellent modification to consider for the Synthex V2.9 board - the ability to solder input, on/off, etc. directly to the board. Just like you do with the USB jack currently. Save a lot of internal wiring. I know my chassis is a scary mess of wires.
And now that I'm thinking about how thin and weak those IDE wires are I'm thinking I need to somehow secure them so they don't simply break over time from the strain of their own weight.