Maybe I’m dreaming, but how amazing would it be if I could use the same shortcut I use to “lengthen [or shorten] note by grid value” to also increase / decrease dynamics, e.g. mf to f, f to ff etc. – simply by selecting them and pressing the shortcut?
Alt-up/down has been suggested, and seems to be a possibility for future updates: Idea: Alt-Up/Down to modify dynamics? - #10 by dspreadbury - Dorico - Steinberg Forums
glad you thought of it before I did 
In fact, someone else had thought of it long before I did, apparently!