It's possible I'm more of a loner than you, so I find the idea of hermits less repugnant.

Maybe I was using too strong a word when I said I found it "repugnant."

be careful you're not imagining these hermits not doing anything fun.

I took your advice and tried to imagine the hermits doing things I like doing when I am alone. That was hard at first, since most of the things I like doing alone still require some other personat some point (reading a book requires an author, for instance). But imagining a hermit studying nature, interacting with plants and animal (the animals obviously have to be bugs and other nonsapient, nonsentient animals to preserve the purity of the scenario, but that's fine with me), doing science experiments, etc, that doesn't seem repugnant at all.

But I still prefer, or am indifferent to, one utility monster hermit vs. many normal hermits, especially if the hermits are all clones living in very similar environments.

On the other hand, clones tend to really mess up my intuitions regardless of the hypothetical. I'm pretty sure they should be penalized for lacking diversity, but as for the actual amount ...

I'm not sure how much I value diversity that isn't appreciated. I think I'd prefer a diverse group of hermits to a nondiverse group, but the fact that the hermits never meet and are unable to appreciate each others diversity seems to make it less valuable to me, the same way a painting that's locked in a room where no one will ever see it is less valuable. That may come back to my belief that value usually needs both an objective and subjective component. On the other hand I might value diversity terminally as well, as I said the fact that no one appreciated the hermit's diversity made it less valuable to me, but not valueless.