Hmmm, this is a rather disappointing thing to read.
When you say the lower back is only strong as its weakest disc, are you referring to the disc itself, or the muscles that stabilize it against forces produced from cycling?
I would prefer to correct or alleviate my back pain by strengthening muscles in the lower back, as opposed to incorporating arm use and posture change. I will still look up Anquetil's style of pedaling, and see what I turn up.
I work at a bike shop, and a senior roadie came in the other day. We talked about lower back pain, and he said that humans just weren't made to ride bikes. Evolution made us to walk upright, not bend over for hours at a time, straining a rather small muscle group continuously. I guess his point correlates with the fact that perfect backs may still suffer....
What the heck I love biking!!! It should be comfortable if I want to hammer on the road all day long!