i use discard markers a fair bit and i have so far not felt like moving something that's not a discard form to the right of a discard marker. it seems to me like it could lead to unexpected consequences:

1. 'a #_ 'b ; 'b is ignored
2. #_ 'a 'b ; now 'a is ignored, but 'b is not

perhaps there are specific cases where you've felt the need? may be i'm missing some good opportunities 🙂

I use it often in hiccup to experiment with different ideas of what should go on a page.

so is it like a toggle between two things then?

Yeah. But maybe it is more common to want the marker to stay with the form it tags. Or more valuable, at least.

i had never thought to try it like that, but now i might 🙂 may be there's something like this in paredit? https://emacs.stackexchange.com/questions/44502/how-to-swap-s-expressions-with-paredit/44521#44521

Yes. ctrl+alt+t in Calva. It happens to be the movement primitive used for the drag forward/backward commands that I use in the GIF above. I tend to use them rather than transpose, because that is how I think about it. ”This should go after/before that”.