It is all a matter of how much money you have to throw at the system.

We set up a micro UAV for the UAV Outback Challenge here in Australia on a hobbyists budget, using the Attopilot.
We tried the Ardupilot without much success, but the Attopilot was a true plug and play system at 10% of the cost of the nearest rival.
And at the comp we saw the nearest rival dive a UAV into the ground at full throttle [:@]

The Attopilot we use is thermopile based but the IMU based version is now available as well.

Support for the product we found was excellent.

Worth a look I would say.
Good luck.

Mike