Jef,
Although i fully agree with your post, I would like also to add the following: the defendants know about the costs of discovery and if one assumes even an unrealistic probability, as of this moment, that their chances of winning is 50% the total expected cost should be considerable. For smalled probabilities of their winning the cost will be even hogher by far. My guess is still that they will settle before of the Markman for amounts close to what DM is asking for.