Like RW says below, cutthroats are addicts.
I do occasionally catch rainbows on hoppers,
but not that often. Cuts and browns, on the other
hand, love'em.

I talked earlier about using a hopper-dropper.
When I do that on the Missouri, for instance
(when conditions are right), at the end of the
day almost 100% of the rainbows I catch
are on the nymph. 2 or 3 browns, at most,
will take the hopper. But those 2-3 browns
are often, by far, the biggest fish of the day.

So, in general terms, I'd say rainbows don't
like hoppers that much. Browns like them
a lot more than rainbows, and cutthroats
can't resist.