Tim,
 
 
> I am also interested in the "theoretical" use of black and white film in
> the age of color, as well as in intermittent use of color or black and
> white (for instance, "Rumblefish") in film.
 
Wim Wender's 'Wings of Desire' is first BW (50-60 mins) then color.
Luc Besson's 'The Big Blue' is also first BW then Color, but only for 15 mins
or so.
 
Both films are really worth watching. Really, really.
 
> Any sources or thoughts on the subject would be appreciated.
 
Sure,
Daniel