I am still old school, 700, 710 and 720 on my 3 bikes. I don't get the whole wide bar thing. I believe 800's do give *some* people more leverage, but for many, spreading your arms out that far actually gives you less leverage, it really comes down to your "wingspan" as to whether or not it will benefit you. If we are going to have a discussion about bar width, it only makes sense if we are going to include a fingertip to fingertip measurement, their height and possibly their cockpit height as well.
So much of this is dependent on geometry of the overall situation. Without that data we're back to the 26" vs. 29" discussion with no indication of the relative advantage based on the rider.
And for the record I am 5' 11" and I'll measure my wingspan once my wife wakes up. If you know what I mean.