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: https://www.steinberg.net/forums/viewtopic.php?f=246&t=145581&p=782782&hilit=dynamics+alt#p782782
glad you thought of it before I did 
In fact, someone else had thought of it long before I did, apparently!