The level of the inequality in pay is at most a factor of 2. I am so, so confident that the woman in those slides will be more than twice as productive, on a range of metrics, than the man. There's a big difference between being competent and being an expert. (In addition, her knowledge about the details of C is good evidence that she's probably going to be more knowledgeable about other things related to the job, too.)
Actually, I believe the oft-quoted factor is 10x productivity when dealing with someone at this skill level (and from what I've seen in the field, I'd believe it). But that implies good architectural sense, which I'd test for before making a final decision.
Barring any serious deficiencies, she'd be a steal at 2x pay.
I think the 10x number is inflated, but one thing I realized more recently is it doesn't matter! If you can get a programmer that is 50% (1.5x) as productive for 2x as much, it's almost certainly worth it, since you are unlikely to get even 50% more productivity by hiring twice as many people (which is the alternative).
