That is mostly the answer. Not exactly old vs new in terms of tech, more of product management philosophy. I am sure the scout was built from a target price backward, "we need this boot', it has to me this price, where do we make it and what is the spec". The Balance, being a trials boot, has little comp, so no real need to have a target price. It is just built with the best spec possible. I know that leather, it is super expensive.
AFA construction, Scout has a molded sole (better for walking, but not resole-able and not as supportive, cheaper leather, less precise fit, and more seams. OTOH it has a stiffer ankle area, because it has a molded in brace. Knowing you and your setup, and how much use you get (Trevor rides a LOT folks) I would lean to the Gaerne. They can be repaired, resoled, and the leather is more durable. If you need more support, I will point you to a lace-up ankle brace.
Don't get me wrong, I like the Scout. But the Balance is a great boot. My fear is that sooner or later they will re-spec it, which will ruin it.