Hi Chad,
I personally think that this requested feature will not gain any benefit for the casual user. I think that there is a tendency to avoid feature bloat in Rockbox, so this feature request has probably low chances of being accepted. You are encouraged to discuss this
over IRC, though.
The F40 have many buttons in comparison to other players, thus there's indeed room for customization, but since TMHO the Rockbox software has so many key bindings, having the possibility to change them will make things more complicated than the way they are now.
If you think there's a better way to organize the key mappings, you are encourage to describe it in details in this forum thread (like you just did), or better - post a patch in Flyspray. If you are not a programmer, you can ask one of the developers to create such patch for you. Try to find
which developers uses this player, and ask for their opinion. I believe they will be happy to commit your patch if it is of any benefit.
Goodluck!