i haven’t read through the other responses yet, but i wanted to make something very clear. there is nothing about the octatrack that makes it sound digital. of everything i’ve made on it, nothing has a cold digital sound. the filter (which i think may even be actually analog) and other effects have a very nice sound to them.
i have a machinedrum, and the octatrack sounds completely different. on top of that, it is a sampler at heart. so there is nothing making it sound digital or analog or whatever. it takes whatever you feed it.
as to your original question, i think the octatrack is perfect for ambient and organic sounds. it can do them very easily. see my post here: The Octatrack can be quite granular-esque [example inside]
you can hear some sound samples at my soundcloud, this one in particular: https://soundcloud.com/nikofeyn/rough-sketch-7-canyon-a-granular-guitar-piece