There may be money available to pay for this development ...
In LinuxSampler please implement a re-pitching facility for existing playing notes. This would be implemented using a channel based MIDI CC (eg CCxx, CurrentNoteyy, NewNotezz.)
The purpose of this is to allow use of a "repitch" option which may be added to software arrangers like One Man Band. This "repitch" capability is how hardware arrangers from Korg and Yamaha work. When a chord change event occurs, instead of re-triggering notes (notOFF, newnote) they repitch currently playing notes especially bass lines, in which case the notes continue sounding at the current time index in the sample but at a new pitch. This technique avoids "glitches" being heard during arranger based chord changes.
I would "sponsor" this development.