Agree in part, disagree in part. In “good” conditions, which for small freestoners means good, relatively high flows, and relatively warm water, say 55-65 deg window, I agree. They’ll eat anything, anytime, just like a Brookie.
But in less than ideal conditions, cold water and/or low, clear water, I find Brookies are MUCH easier to catch in mixed population streams. Even in streams I know for a fact are 75% or more Browns, I catch a disproportionate number of Brookies in “off” conditions. In low, clear water Brookies can still be observed out in feeding lies. They spook easy, but if you don’t spook them, they are still easily caught. Browns are ghosts. It’s not that they’re selective about what they eat, they’re selective about when they eat. And in low/clear water, they’re just not eating at all. During the daytime anyway. They’re under rocks, in rootballs or undercuts, or jammed into bedrock faults. I think this largely has to do with how they evolved. Brookies in infertile Appalachian mountain environments…”I need to eat everything that even remotely might be food, all the time.” Browns in more fertile environments in Europe (depends on the strain to some degree, but figuring ours are mutts at this point, at least true to some degree)…”I can gorge when I want (aka, when it’s safe) to eat, and fast when I don’t want to.” Ever notice how fat small stream Browns are after a mid-Summer bump in flows?