I sold my HK 650MM Hexacopter and used the money to buy the combo below the Arris M680 Hexacopter. I have ordered (6) 16MMX14MMX330MM carbon fiber tube to convert it into a 810MM Hexacopter. This will allow me to swing up to 15" props with the included motors. I"m still waiting on parts to get here and hopefully that will be next week sometimes.
http://www.arrishobby.com/arris-m680-carbon-fiber-hexacopter-super-combo-not-assembled-p-777
http://www.arrishobby.com/arris-m680-carbon-fiber-hexacopter-super-combo-not-assembled-p-777