The LyCon flat air cooled engines belong in museums and restored
MM-era bug smashers, nowhere else. I saw a composite biplane built to
very detailed skin perfection in one of the crappy "popular science"
magazines-it was built by some guy who works for Rutan- and I actually
started laughing out loud when I saw that stupid 1920's era
construction overgrown lawnmower engine under the cowling.

The Harley engine is obsolete and overpriced, but nowhere nearly as
much as anything nominally out of Williamsport. (I say nominally
because they don't even make anything anymore-they outsource
everything, often to the same companies that make aftermarket H-D and
Chevy parts.)