Good question. This tech can be good or just get you punished. If there's platforms, it tends to help you better than without them
I mainly use this with mario and luigis down throw, but I would be careful with this. I got into the habit of doing it to marios down throw every time, and I get regrabbed every single time, and take like 40%. Please just DI down and away and shield for that, don't side b cancel unless it's battlefield or delfino, something like that, because you'll land away from him on a platform.
Same with luigi, just be aware you more than likely won't hit them, I have hit them, but not often.
I want to try to test things to see with certain DI, percentages, timing, things like that, if you can get a guaranteed hit.
If I find something I'll be sure to share it
Other than some throws, It can be used to escape multi hit moves, a lot of them don't get you out, but, with Donkey kongs up b on the ground, you can do the tech and hit him at the end of the up b