Ah, so what would essentially happen then is that releasing a phrase would cause the notes within the phrase to have legato applied to them (as ghost noting is essentially legato)?
I think this would be slightly “hard to use” - it would definitely have interesting results, but I fear they would be hard to control and sometimes undesirable.
The alternative I think is better, to simply apply a gradual velocity ramping to the phrase - just as if you had written a string of velocity commands in the pattern editor (but of course applied to the phrase using it’s own LPB setting). The ramping itself could be specified somehow, as you point out.
Well, at least ramping the velocity would open the door to the possibility that the plugin or synth might treat a lower velocity as something which should affect the timbre of the sound. And since this is also possible with the sampler, I’d say it’s a pretty good all-round solution
Such a thing could go nicely hand-in-hand with an option to create a loop within a phrase