Great Idea! ~ 25% of the mass
Great Idea! ~ 25% of the mass of a conventional Engine, and 25% Less Spinning Mass sounds great! Is there a Running Example on a Test Bench yet? I have seen running examples of aviation 'New' Engines for years at EAA air Venture Oshkosh, and it take quite some time for some of these things to get delivered, but it depends on the level of simplicity, cost to build, urgent need by a target market for uptake, and so on.
Still - from first looks - this sounds very promising, and even can be build in a Hybrid integration style - like the Pancake motor of the Honda IMA system! (That could take car of any throttle response questions, too!)
Personally - I see this as a tool for a major improvement for Series Hybrid Vehicles like the Via Motors VTrux product! Weight Reduction, Smoothness, build Simplicity! Great!