My fear is that Mach4 screens will be specific to a user's particular setup and hardware, and will not be easy to share with others.
(Meaning that they'll be easy to share, but may not work for others)
Having worked with both MACH3 and MACH4 screens, I would say MACH4 will be more difficult to make 'universal' but certainly not impossible. Unconfigurable screens created for specific purpose would not transfer well, obviously, but if the goal from the beginning of the project is to make a configurable (i.e. saleable) MACH4 screen set, I have not run into anything that would prevent that.
In the same way the Kflop is far more powerful that smoothstepper, that capability comes at a cost. You cannot integrate a Kflop with 'checkbox programming'. MACH4 screens taste like that to me. Making a purpose built MACH4 screen is not difficult or complicated, but to create a configurable set is an entirely different and far more complicated task.
The stumbling block, in my view, will be writing a configurator to fill the boatload of parameters that would be needed for a 'universal' screen set. For MACH specifically, I have written configurators in VB script , C# and C++ (for Windows programs), and now in LUA, both stand alone and 'widgets'. The first widget too far longer than ALL of the screen mods. There is some documentation available now that should make this mine field less painful to navigate.