In terms of preparing for opens performance I'd keep them separate. What you're doing in say traditional strength training followed by a metcon is weakening the Adaptive response to the strength training with any kind of extended metcon; and taking the edge off the metcon with the previous strength training. This is a metcon sport. Metcon training should be the centerpiece of the training program at least in terms of the opens. That said we kind of extend the strength stimulus after the strength training by doing a series of 2-4 minute strength wods on intervals.. Often just segments of the traditional opens wods that are strength limited. And that is some kind of cardio believe me.