After some painstaking PID tuning and some near crashes, I decided to take out my octocopter and see what kind of thrust it was able to generate. After hovering for a moment, I gunned the throttle and the machine disappeared into the sky. It was beautiful. The only problem was that I had forgotten my Xbee receiver and thus had no telemetry data. My glee quickly turned into panic as I tried to judge which way the octo was facing and how to get it back. As it drifted further and further with the wind, I collected myself and started to lower the throttle. It grew larger for a moment but I knew it was still drifting. I tested pitching backwards, to see if it would get closer, then pitched forwards.... forwards was the trick and it moved back within a comfortable range.
Moral: Never fly without telemetry OR a spotter. I had neither and my very expensive prototype almost disappeared forever because of it.