If you are going to ignore my comment about the rudder, then here is a comment about the DX6i:
NOTE: When Flaperon or Delta Wing type is selected, the travel adjustment is used to adjust the
individual servo throw, while the combined aileron travel is adjusted with the aileron dual rate. It
is also possible to set aileron differential. Reverse switches are applicable for each servo. Neutral
adjustments of each servo are made by the Sub Trim Function.
Taken from page 44 of the DX6i Radio Programming Guide. A copy of which can be found here:
[link]http://www.squadronleader.co.uk/pub/files/Accessories/Spektrum/1215619156_DX6i%20Manual.pdf[/link]
It seems that you have to adjust your dual rates. to get your full deflection.
Rafael