This doesn't work as out of a man and woman of the same weight the man will still be stronger on average. Women have a higher body fat percentage, and less muscle in their upper body simply because they have less testosterone. You would probably have to use testosterone as a way of categorizing people in sport. It sucks but there is no other fair way I can see.
A little late, but I think I have a reasonable solution to the genderless weight class classification.
Measuring the hit force of athletes for sports like boxing could work. Not sure how viable that is in real world applications, with human nature and all, but it seems reasonable to me. If the issue is men on average hit harder than women of similar builds, why not just classify by hit force instead?