I know 3 or 4 guys who have a 0-wt, but nobody who owns a 1-wt, so my experience is quite different from yours.

I fish a lot of small streams that contain smallish fish. Where I mostly use my 0-wt, I can pretty well guarantee that I'll catch nothing bigger than a 10" trout. I was surprised on one creek, to catch a cutthroat of 13 inches, and the 0-wt still handled that fish with ease.

The 0-wt is not a toy. Its built for delicate presentations but still has what it takes to land a good sized fish.