The science behind it for some history. 10 years on female hormones will remove almost all muscular advantage given as a man at birth. However

1 - Does it affect lung capacity (a big difference)
2 - The mental factor. This may come accross as insulting but womans dh is pretty dull. The reason being is in the non pro classes and even some pros don't go fast enough or hard enough to catch lots of air required to be REALLY fast. Excluding some very elite few. This mental factor is still with Michelle giving her a pretty good advantage in the 'taking chances' category.
3 - Size factor...she is still a big girl. Bigger than most. Weight? Other things like that. Maybe muscular distribution is 'relative' but is it equal.

Lots of questions and way to indepth to really get into. I haveno negative reactions to her personally. But it does seems a little unfair on the surface. 20years as a man and 10 years as a woman...Iam sure there is some advantage...