Perhaps I'm doing something wrong, but the "boobs to the tube" method doesn't seem to work for me. When I lean too far forward on a climb, my diaphragm feels like it's getting smooshed and I can't breathe well. I have to do the exact opposite, and sit very tall and upright with totally relaxed shoulders and light hands on the bars. This opens up my chest and lungs so that I can take in nice deep breaths. With all that being said, I still suck at climbs. 
Linda
2012 Seven Axiom SL - Specialized Ruby SL 155