It seems to me >that the latter technique lends itself best to portraits and >landscapes and is essentially unsuitable for, say, street >shooting.
You guys are all infants. I'm 83, I've been doing street photography since 1953, and I'm here to tell Jim that not only is the tripod technique essentially unsuitable for street shooting, the D800 is essentially unsuitable for street shooting. To do effective street photography you have to make yourself non-threatening. With a camera as large as the D800 you simply aren't non-threatening. The Leica is ideal but nowadays its price is absurd. I've found that the best thing around for street is a four-thirds camera with a Leica-branded lens. I love my D800, but it stays home when I'm on the street.