I've only recently started using this technique, so I don't have a whole lot of experience with it yet, but I like it so far.
I don't have a tillering tree, not because I can't make one, I just havn't found enough reason to get me to make one yet.
Because of this, I've experimented with 'hand' tillering techniques. I gotten to the point that I can tiller a bow mostly by how it looks at floor tiller and brace. This makes for a useful skill when tillering out in the woods and working on primitive bows.
By looking at and feeling the taper of the limbs, I can get a bow pretty close to correct tiller.
I also like to use a mirror, and flip the bow around and upside down and downside up and every which way.
Sean