Hmmm I'm trying to change the mode color in #vim and these lines work but the last one does not as it needs double quotes but you can't use them there.
set statusline+=%#DiffAdd#%{(mode()=='n')?'\ \ NORMAL\ ':''}
set statusline+=%#Color458588#%{(mode()=='i')?'\ \ INSERT\ ':''}
set statusline+=%#ReplaceColor#%{(mode()=='R')?'\ \ REPLACE\ ':''}
set statusline+=%#VisualColor#%{(mode()=='v')?'\ \ VISUAL\ ':''}
set statusline+=%#PmenuSel#%{(mode()=='\<C-V>')?'\ \ BLOCK\ ':''}