I'd only be nervous crossing off ramps getting a car exiting at 70 while you're crossing it to get to the other side of it and back on the shoulder. I've ridden many 4 lane highways with medians, and actually love it, most cars go out of their way to avoid passing too close, the climbs are graded, wind block from said graded hills, and the draft from the passing cars gets you going at a pretty nice clip.