Re: Why no tsuba?
David, just to give you the courtesy of a reply: Knowing that O-Sensei didn't used a tsuba means to me that if I were studying sword from O-Sensei, I wouldn't use a tsuba. Knowing that Iwama doesn't use a tsuba means to me that if I were studying sword from Saito Sensei's school, I wouldn't use a tsuba. Since the lineage I study uses a tsuba, I use a tsuba.
Arguing about how one's better than the other seems fairly fatuous to me. It's better not to wear a helmet on a bicycle because then you'll be more careful? Wearing armor means no one is going to target your elbows (or knees)? Cheez.