I used Ableton’s Stretch MIDI function often. You can hear it clearly in my song You Are Disturbing from my 2007 album Attack Decay. The main synth line switches from single to double speed. There is another detailed post on Wire to the Ear about Stretch MIDI notes from April 2008 titled “use the stretch notes command in ableton live” which you can read: click here. I think it’s a great and useful songwriting feature so it was definitely worth a revisit.
“The Stretch MIDI Notes feature allows the user to take a selected group of MIDI notes and stretch their duration, a lot like how you are able to stretch warped audio. You can either lengthen or shorten the duration of the selected notes, and even better is that you don’t have to select every single note in the clip in order to start stretching… that way you can stretch the timing of the kicks and hi-hats without altering the timing of the snares for instance. All you need to do is select a note (or several, or all notes) in your MIDI clip, then right click in the clip, and at the bottom of the contextual menu you will see Stretch MIDI Notes!” – Thavius Beck