As it turns out, the new cases cost significantly less than the cheapest new unprimed conventional brass.
Other benefits cited (assuming that the new new cases turn out to be all that they're cracked up to be): They weigh almost exactly half as much, you can have the case heads anodized to just about any color you can imagine for easy load identification, five to ten times the number of reloads, case trimming is no longer needed, you can generate higher velocities with lower pressure, they have slightly greater internal capacity, the magnet thing, and larger and beveled flash hole to get better and more consistent ignition.
The liabilities cited are that they require the specialized dies that cost about twice as much as conventional dies, they require case lube, pulling the bullets compromises the cases and necessitates they be discarded.
We already know that these new cases cost quite a bit less than regular brass, so if you really can get at least 40 reloads apiece with them, you'll be reloading for less than with regular brass, considerably less.
It's also worth commenting that the specialized dies for these cases also work with regular brass, so anyone who doesn't already have the dies for regular brass who wants to try these new cases first will have no problem going back to the regular brass if he wants to expend it or if the new cases prove unsatisfactory.