I haven't joined yet. I was out of town for a year long internship, so I'm gonna go to the next monthly meeting and I'll pay my dues. And yah, I've heard Bjorn would guest speak, do workshops, etc, but I'm not sure if he's very involved any more with his move to Nashville.
The sizing is a bit weird (it ranges a bit beyond the 5-10 mm which was advertised, maybe 2.5 to 9-10 mm), which I expected with it being bulk/ cheap but other than that it looks fine (with my limited experience). There really isn't much dust in the bottom of the bag and it isn't just a bag of muddy twigs so I'm pretty happy for $30.