> Sounds like they're trading the spark system (a pretty easy to maintain system) for a second piston/crankshaft/etc. Opposing pistons and compression ignition

> Sounds like they're trading the spark system (a pretty easy to maintain system) for a second piston/crankshaft/etc. Opposing pistons and compression ignition are (mostly) orthogonal optimizations. From years of working on engines, I'd also be more willing to call the mechanical parts "perfected" and the ignition system "not perfected", at least for common consumer engines.