[jonfields45]

When I was thinking about flax fiber robustness, I was not thinking about temperature resistance, but rather mechanical stability of a hydrophilic (absorbs water) fiber. I played an early El Capitan and it had high action and no bridge saddle left to sand. The store owner was quite excited about that guitar and I chose to say nothing (more polite that my usual? :~). It did look and sound great.

CF and Glass fibers are hydrophobic (don't mix with or absorb water). Epoxy's characteristics depend on the specific compound, but the stuff we used in semiconductor packaging (in my day) had to be dry packed to keep it from absorbing water and exploding when subjected to heat for soldering. Clearly the stuff they paint boats with is hydrophobic.

In any case, organic fiber in composite build-ups is still relatively new technology. Until you build, age, and cycle some guitars at various temperatures and humidities, you don't know for sure how it's going to hold up.

Presumably today's eKoa guitars are past this point in their development.

Flax/Linen is relatively expensive stuff. I can't wait for hemp guitars!