Many synths can be loaded in standalone. Then they can be connected to projects by virtual midi.

Templates is working indeed in general, but for the flexibility I described, it is not appropriate.
My project has something like 15 to 20 Go of loaded sound, so the problem is about loading time (from one project to the other) more than presets itself.
 
Virtual midi could be a solution indeed,  I have to thing about it :)
Maybe two computer too, but it is another story...

Probably not ideal, but you could load each individual project into one MASS Project.  Separated either by using different tracks or by putting the songs one after another and using Time Markers.
 
This would utilize the same settings, sounds, and instruments, but would involve manually copying each separate song into the one huge project.

francois_1
Templates is working indeed in general, but for the flexibility I described, it is not appropriate.
My project has something like 15 to 20 Go of loaded sound, so the problem is about loading time (from one project to the other) more than presets itself.
 
Virtual midi could be a solution indeed,  I have to thing about it :)
Maybe two computer too, but it is another story...

Project Templates are not about presets.
Its about loaded VST's and VST plug ins all ready to go at the drop of a dime.
If you open all these projects, there is no loading time.
 
You might need to explain yourself a bit clearer in order to receive the best possible solution.
For example: Why not put all these projects in the same project and export them in separate data files ?
Why the need for multiple open projects using the same exact plug ins, synths, exc.
And what is " "standard" sounds" ?