Can't say I was ever a big Pigpen fan -- but my recent re-immersion in all things Dead has given me a much higher opinion.
Check out 2-19-71, the first show after Mickey's abrupt departure. Jerry sounds a little confused, forgetting lyrics like it's 1993, and at first it sounds like everybody's trying too hard. But Pigpen rallies the band and saves the day. Would you believe "Smokestack Lightning" is a highlight? I never thought I'd say that. But it is. And Pig's even better in the second set.
Greg K: The last Dick's Picks from before the hiatus are #31, August '74, and #7, September '74. Haven't heard either. I'm tempted by #12, from June '74, because the shows I've heard from that month are among my favorites.