Bump. Whenever I really need Redo, it doesn't actually work because SE is so aggressive about discarding the content Redo stack whenever any kind of movement occurs. Even just clicking the mouse discards the content Redo stack.
This has forced me to try to change my workflow. To be successful at that I have to remember ahead of time that SE discards the content Redo stack aggressively, before I hit Undo in the first place. So what I do now is basically hit Save every couple of lines. Which pollutes the SE backup history and reduces its effectiveness (sifting through 120 "revisions" from a single day to try to find something is awkward).
It's not uncommon for me to hold down Undo for a bit, accidentally overshoot where I meant to go, but need to move the cursor to be able to detect that I overshot. And once I've done that there's nothing I can do about having overshot, the Redo stack is already gone. If I'm lucky the SE backup history will have the changes I'm looking for, but it's cumbersome to try to find what I'm looking for that way (because the lack of Redo has made me save every couple of lines). I end up using Save As, then open several backup files and Save As each of them to temp files, then close SE without saving (saving could potentially nuke the only copy of the text and force me to reinvent it). Then I use other tools to compare the several files and extract the bits I need and use another editor to get the file to have the right content again. Then I launch SE again and continue.
It's not the highest priority, but it's a bit of an "in your face" fit and finish item. Hopefully it can be addressed before too long.