Now that I'm back from a trip to Boston/NYC/London/Paris, time to look at building a more complex Arduino control system. As I have been increasingly looking to UAV development to help as the basis for the development of low-cost and responsive autonomous spacecraft and rocketry, I have come across these Hexacopter kits from 3DR and jDrones...

Doesn't seem to be much in terms of spec difference at least for my uses. It seems like the basic platform is there, but the real items that set this apart such as IR, Sonar, long-distance TX/RX still seem to be options which doesn't make much sense but still look like they can be bolted on. Comparing the two specs gives the following:

From jDrones, including IMU, flight control, non-uBlox GPS and magnetometers -

ArduCopter Hexa v1.0 - Fully featured UAV development platform.

1 x ArduCopter Hexa v1.0 24" Frame (28cm arms)

6 x Motors designed to ArduCopter use, 850kv (can be changed to bigger)

6 x ESCs designed to ArduCopter use, 20Amp

6 x Propellers designed to ArduCopter use, 10x45 (can be changed to bigger)

4 x HighRise 20cm landing gears

1 x ArduPilot Mega Flight controller board

1 x ArduPilot Mega OilPan IMU board

1 x Connectors/Cables between APM + IMU

1 x Set of 3 row pins for APM

1 x MediaTek 3329 GPS + 10 cm Cable

1 x HMC Magnetometer + 5 cm Cable

Everything else not listed here are optional and ArduCopter can be expanded with them of users can build their own expansions. Eg. this kit does not contain: Camera, Video systems, Batteries, Radio or other devices. Needs: Radio, Receiver and Battery to make it fly

From 3DR incl sonar bracket and uBlox but no sensors (roughly $35 for the sonar unit itself though not sure re range)

3DR ArduCopter Hexa-B - Fully featured UAV development platform.

ArduCopter Hexa 3DR KIT, Electronics Contains the following:

2 Fiberglass Main frame boards 

7 Aluminum arms, 5 Black arms and 2 blue arms

2 Fiberglass Carrier boards

Fiberglass Landing gear

Power distribution board, power cables and signal cables for PDB-APM

All hardware needed to assemble the components above

6 Motors (850 or 880Kv)

6 ESCs

6 Propellers (either 10x47 or 11x47)

Ardupilot Mega 2.5 kit unassembled with choice of connectors and GPS unit (regular MediaTek or uBlox)

This Hexacopter kit is based off the 3DR ArduCopter Quad. With two extra motors the lifting capacity is increased to over 1kg. The PDB still mounts neatly between the base plates but access to it is made easier by thumb nuts that easily unscrew to remove the stackup. This also lets you attach and remove APM with screws more easily.