Mini Flame Quadcopter frame with 3 degree anhedral angle

After test flying the original design http://www.thingiverse.com/thing:34552 model ,I think top and bottom platform make some modifiy will make flying more stable , so I design a top and bottom flatform with degree anhedral angle .I have no experience that which angle is the best ,maybe 3° , 2°,or maybe 1°. I try 3° this time ,so I will provide the Freecad file ，everyone can change the angle easily .