Thanks for your 5c, I stopped using small coinage too :)
Here is latest iteration:
RAMPS-FD-v3_2 by donotdespisethesnake, on Flickr
Here is a reverse view
RAMPS-FD-v3_2-rev by donotdespisethesnake, on Flickr
I think I got most or all of your suggestions. X Y and Z are on same port, both Mega and Due. I'm not sure Z really needs two connectors, but there is probably space for two. There is still a bit of jiggle room, the board could be extended to add a 5th FET, or alternatively trimmed back slightly. Possibly there is excess space at the centre, but I still have some components to place.
I added 3 blade type fuses, don't know if that is overkill.
This version is nearly compatible with Mega, with the exception of SPI which appears to be on completely different pins. The simplest thing may be to add a second SPI connector.
I also have an idea to create an expansion board which could add 4 stepper/extruders
Here is latest iteration:

RAMPS-FD-v3_2 by donotdespisethesnake, on Flickr
Here is a reverse view

RAMPS-FD-v3_2-rev by donotdespisethesnake, on Flickr
I think I got most or all of your suggestions. X Y and Z are on same port, both Mega and Due. I'm not sure Z really needs two connectors, but there is probably space for two. There is still a bit of jiggle room, the board could be extended to add a 5th FET, or alternatively trimmed back slightly. Possibly there is excess space at the centre, but I still have some components to place.
I added 3 blade type fuses, don't know if that is overkill.
This version is nearly compatible with Mega, with the exception of SPI which appears to be on completely different pins. The simplest thing may be to add a second SPI connector.
I also have an idea to create an expansion board which could add 4 stepper/extruders