As I understand it, the benefit of D-H3 fusion is the complete absense of neutrons. The other fusion reactors would require shielding. The neutrons would also damage the container more quickly (in addition to making it radioactive), reducing the operational life of the device.. Since much of the energy of other fusion reactions is lost via the neutron, D-H3 leaves more usable energy, and removes the radioactive waste issue completely.

I realize that Popular Mechanics is a pie in the sky kind of publication, but that doesn't alter the fact that serious He3 research is ongoing. Given that Jack Schmitt testified in Washington in favor of He3 research (specifically, mining the Lunar regolith to get it), then it can not be considered a crackpot idea. There's nothing wrong with writing about visions of the future, as long as you don't confuse it with today's reality.