How about Insert Row / Insert All Rows and Delete Row / Delete All Rows? The "all rows" variants do the same thing for all channels covered by the current selection.

I want to use the feature mainly to move notes around when I've messed up their placement (bad timing when recording for example) or experimenting with the notes, and also to move effects around to create interesting... effects.

While the insert/delete row functionality is pretty useful for some things I can't use it to accomplish what I'm trying to do. Which is:

When moving a note, I want to move only that note. Insert/delete rows changes everything below the selection which isn't ideal. Instead I want to be able to move a note (and its properties) or a single instrument/volume/effect value up or down without changing anything else in the column. Kind of like the drag/drop functionality except that you can't change the channel by accident, and that you don't have to select the whole row in order to move a note.

Selecting with the mouse and editing with the keyboard would make my workflow a lot faster, so that's why I'm requesting this feature.

I recently started looking into this, but the way I imagined it to work (use the selection key, i.e. Shift, together with cursor keys) didn't quite work for technical reasons. Oh well, maybe there will be other ways.

I remember mentioning the exact same thing in IRC recently, yes this feels like a really basic and necessary feature, should be done ASAP ;)