I had some. It goes a tad faster, and shot into the smallest groups I've ever had from factory ammo. Consistently. And, for what it's worth, the velocities were very consistent as well. But, Hornady techs say they had to do compressed loads, and that was problematical for mass production - bullet slip, powder spills, not fun in a plant - and now, their new SuperPerformance stuff is consistently faster, supposedly accurate, and is not only not a compressed charge, it is consistently below SAAMI specs for pressure. They are introducing it in most popular calibers first, and I reckon it will be while before it is commonly available in gunshops, but I'd like to give it a try.
In the meantime, if you find some Light Magnum, in sufficient numbers to sight your rifle, test true trajectory, and still go hunting, go for it. You won't be disappointed. Poorer, but not disappointed.