If you have a corked and caged bottle one thing is to consider is that if the beer is in contact with the cork, you run chances of some of the beer becoming "corked". 3 to 4% of the cork has the fungus that causes the off flavor/aroma.
Paul as to the yeast consuming all of the O2, I used to believe that. When we toured Bells Comstock facility at a AHA rally, John Mallet, the production manager (and a winner of the Ress Scherrer award for inovations in brewing) had some comments. First he said that they double CO2 purge the bottles to get the air out, fill, and then give a squirt of water (IIRC) to cause foam, and they cap on foam (CO2 bubbles). They bottle condition, but the yeast are viable and do not need O2. If there were O2 in the headspace, he claimed the yeast would only use about 1/3 of it, and the shelf life of the beer would suffer. If they go to great lengths to eliminate O2 when bottle conditioning, there is a reason.