Lessons
Cost/Complexity per monitor vs Depth of Deployment Tradeoff
c.f. Metcalf and/or Reed
1ms is ushally enough, RTT will mostly tell the story
the more samples the less history

Large scale infrastructure is difficult but doable
96/4 rule
solid state

Reputation matters if you want people to deploy your box

There is a big demand for active measurement
lots of network operators
the more general you try to be the less likley you'll fly

Humans can be useful too