They are unpressurized piston planes, never been a fan of flying above o2 range, shoving junk into my nose and hauling o2 tanks, homie don't play that game.
But to the topic, flown both, including light 206s (including u206s with 550s and extensions), I bought a A185F on edo amphibs, works great for my mission, if you know how to fly those floats you'll be able to get in most anywhere and still get a hair over 120ktas. On wheels she'll land damn near anywhere too.
Unless you really need that rear cargo door the 185 is the top dog.