I would suggest the Century Swift NX as it can easily be set up for LONG, very stable flights using their 600+ motor, 9T pinion their 85A ESC set at 80% using 560 or even 570mm blades.

There are fellows using them for photo work that get 15 minute flights using 6000 mah packs.

Here is a video of one:

http://www.youtube.com/watch?v=Jzh3nhfJLrM

Set at a higher head speed (100% ESC) and a simple change to 3D paddles will give you this:

http://www.youtube.com/watch?v=xijoSIekxQ0

These are of the Swift 16, it has now been replaced by NX which is even better with the Battery pack under the canopy instead of under the mainframe.