(I have used both Acme and Emacs but only a little bit each) I can believe that most of the time it is easier to switch to the mouse to move the cursor where you want if it is no where near your current position. But what about just moving up and down one or two lines? Do you really just use Ctrl-A twice to go up a line? Or do you use the mouse? Or is there some alternative that I haven't heard yet?
As you say, there are great use cases for just having a simple keyboard shortcut. Ron Minnich made "smacme", a modified acme with the basic Emacs C-f, C-b, C-n, C-p bindings in; you can find it in the sources directory IIRC, but in any case it's really a pretty simple hack.
I've only found a reference in a 2006 post from Ron. Is it a modification to acme which would need to be ported to plan9port or is it already part of plan9port's acme or is it maybe just a set of scripts to source on acme startup?
http://acme.cat-v.org/keyboard
(oh and I really miss moving back and forth by word and incremental search with keyboard, I have nothing against using mouse for other things though)