Re: Swift River Massachusetts
I can confirm that I saw people slaying with the San Juan worm, pink and white.
If you move down river from the Y fork it seems less busy. I was there on a Saturday my most recent time, there were maybe 4 at the Y fork, a couple people up river, and two or three down river, but even further down (still great wading) it was fairly empty for good stretches. Everyone seemed pretty nice and were trading flies.