Charles - MDF is incredibly dense and stable. It’s basically just fine wood dust and glue compressed. It doesn’t have terrific structural rigidity though, which is why internal bracing is needed if the individual pieces are longer than about 16”. One area where Axiom might be able to improve upon is going with thicker stock, like 1” or 1.25”. I suspect it isn’t necessary though and the extra width will just make things heavier and more expensive to ship. One advantage bamboo might have over MDF is weight. I’m pretty sure that by volume, MDF is heavier. If I were to build a speaker cabinet, my first choice would be MDF and cost has nothing to do with that choice. Another advantage MDF has over other sheet goods is that it is about as close to perfectly flat as you can get. This makes it great for laminate, veneer or vinyl. It is also very easy to work with if you use carbide tooling. Miserably dusty though. It takes a great dust collection system to make the work area tolerable. The dust gets everywhere and is horrid to breath.
BTW – keep the ideas coming. I’m keeping track of them, even if no one else is.