HeatUp is a pretty good reference for many things. Maybe something like FL Studios Piano Roll would fit better. With less functionality as the original but better as the one in HeatUp. At least, cut, copy, paste and duplicate hotkeys would do the job.
(ctrl+ x;c;v;b)
And of course the ability to select/deselect notes.
It's a different workflow to have a note editor like this as arp, but a fast and free workflow. Upvoted!