I think an engine such as this would quell all talk of using chemical propulsion. Heck, I think this would be a good engine for an orbital transfer vehicle. Of course this would be good for long range probes running off an RTG power source for a few thousand years, but serious thrust ?
Use an Orion drive, the radioactive way to fly.
This is an excellent engine, a spacecraft using this engine to go to Mars (probably nuclear power source) could probably do it in half the time of a comparable chemical-powered spacecraft. Of course Orion is the Uber-Engine which unfortunately would be plagued by Uber-political problems. Robert Zubrin proposed a Nuclear Salt Water Rocket design that would not be plagued by the problems of the Orion treaty-buster problems. Plus it's operating efficiency would surpass even Orion's capabilities. If Nasa ever gets around to building such a spacecraft, that means they are very serious about manned space exploration, but I'm not holding my breath on that one. ;)
Nuke Your Way to the Stars