Great to hear but BrainTrust (and perhaps the creator can step in and clarify) was focused around groups of people originally until A/B testing and the ever-present need to make some income pushed it towards companies/project teams. BrainTrust has group feeds and per file discussion which DropBox does not as you've said (different focuses). Nonetheless I look forward to seeing how you guys overcome these barriers so I can selfishly learn from your approach.