I think Orvis had (or have?) a 00wt. fly rod if memory serves. For several years, I fished 2 and 3 wt. fly rods all season long. Since I'm only an hour from Canada's biggest city, I found pressure on these streams increasing and as a result, a fresh approach was req. for pressured fish. Namely, streamers.
I don't fish now as much as I'd like, but when I do, it has to be a 4wt. or 5wt. fly rod to launch bigger streamers~even on very small creeks. The down side is that an 8" trout doesn't feel like much on an 8' 5wt. The UP side is that you'll find some impressive trout fishing streamers~even in creeks narrow enough to jump across.
My 2wts. are gone, one of my 3wts. is for sale.