Unbelievably, but true, I've done each of them, in the same year, too. Well, the Trek was a 1980, but same diff more or less, see here:

http://www.fixedgeargallery.com/2004/e/cowen.htm

I really liked the trek, really comfortable and fit great, the Tempo was waay stiff, (if you like that kind of thing ), Tempo was about 4 pounds lighter in fixed trim.