When I ride my 700c I basically use the inner two rings unless I am riding a long way downhill. So I think I could get by with the right rig. But I don't really see the point of dropping a ring when triples are cheap, and the added weight is pretty minimal. Also, I think the double would probably tempt me to use 9 speed or 10 speed cassettes, while I think 8 is about optimal, though I could use 8, I am just saying I think I would be tempted otherwise.

If these guys made an all silver double I would be tempted to use it one a 26" touring build just for the bling.

http://www.whiteind.com/cranks/mountaincranks.html