You are right to be skeptical. We've been down this road of lots of promises for new technology before. If there was an problem with the design the company isn't letting us know. Maybe its durability? Torque? repairability?

Reminds me of the "orbital engine" out of australia last century that had some challenges it couldn't overcome. There are lots of other attempts to make different engines.

http://en.wikipedia.org/wiki/Orbital_engine

Alternative engines are always interesting though, and who knows?