Try putting the mappings in ~/.gvimrc instead. Does that work?
Björn
Good.
You maight want to take a look at ":h macvim-shortcuts" for a list of
what keybinding MacVim sets up and how you can disable them. Note
that some Cmd-keys are bound to menus, see ":h macvim-menus" on how to
free them up.
Björn