I was looking for a way to reverse a sample on the fly from a midi controller.
First, I investigated the Reason stock devices that are able to load samples. Some of them have a reverse function that allows to reverse the sample before it is played because the device has access to the sample data beforehand.
- Kong/NN-Nano/NurseRex
- Dr. Octorex (reverse slices)
- NN-XT

Of course, one could use the poor man´s approach and duplicate the sample, reverse one of them and switch between them.
Next, I´d a look at some FX REs. So far, I found the following that reverse audio on the fly during sample playback (which is a bit of a downside):
- ochenk Glitch Effect
- Peff Buffre Beat Repeater
- Propellerhead Polar (Rev Loop?)
So, my way to go would be to use Glitch Effect or Buffre that I own.
What works for you?