I am reasonably happy in Darion for the moment, though the time to move on will come sooner rather than later, since most things are gradually getting cleared out.
I guess I was worried that if I don't do this Island quest early enough I might miss something important that I should have from early on to gain the full benefit (such as something enabling me to unlock the other 2 spirits of rage, so that they can begin advancing early and thus be useful later in the game - or something else along those lines).
But yes, I am gradually beginning to run out of things to kill (indeed, other than those mentioned as too powerful). This is also partially, because I am sometimes reluctant to kill things that I think might effect quests I might later receive. For example, I am avoiding attacking any hero-stacks, because I fear that there might be quests to kill them later that I have not yet received and that I would miss out on if I kill them now. (BTW: The devs really had a sense of humor when naming some of those!
)
I have got to say, though, this game is excellent - I am really enjoying it.