I was just talking to my buddy about this the other day. I definitely recognize the names of those who post often, and it really isn't that many....I wonder how many people have subscriptions with BPL? If I had to guess, I would say 300 or so - but I really have no idea.
I backpack with a group of guys on a regular basis, and only one of them weighs stuff like me. He isn't quite as crazy as me with dropping weight, but he is getting there. Although it is growing, I don't think many people are "really" into the UL thing.
As for the sub 5 lb pack, I don't even find it that hard to achieve in good weather and a minimalist approach. But, I have to admit, I'm usually at 7.5 lbs, and it's quite comfy.