Well there's no more redundency with a 9503 or an 11X than there is with a DX7.
What you do get is more rich and powerful programming, much better feeling gimbals (the DX7 feels like an AirHogs toy in comparison) a bigger screen with live graphs for all functions like pitch curves, throttle curves, expo and dual rates.
As for the differences in the 9503 and 11X its the same, more mixing, multi surface servo balancing, user configurable menus, switch assignments etc. For example to assign a switch on the 11X all you do is bring up the screen and flick the switch. Another stand out feature is the SDCard compatibility, you can store models on the card and update the firmware via the SDCard and swap models around to different 11x transmitters.
Oh yea, and more channels
which can be used to assign dual ailerons, dual elevators, dual throttles etc in a very easy to setup interface.
If you have the money get the 11. The 9503 is a nice upgrade of the DX.
Oh and both the 9503 and 11X have a back lit screen which doesnt sound like much but once you think about how many times you have to move a 9303 or DX7 in to the light to see the screen its got definate value.