You can very quickly check multiple Nebula programs in order to find the right one.
Load the first program (Add program(s)). Select it in the Master FX dock and press "Start".
Now press [Option]/[Alt]+Down
Selected FX program will be replaced with a next program from the Nebula repository. Audio playback will immediately reflect a newly loaded program. Just press the same keyboard shortcut again and again to travel thru programs. You can also use [Option]/[Alt]+Up shortcut to travel backwards.