It's mostly a reminder/pointer for the pad across all games, but don't just look at the paddles as duplicates - think of putting bumpers or d-pads on face buttons, and face buttons on d-pad inputs. The true versatility isn't achieved by just leaving all the other inputs as they are.
...having said that, my actual set-up for Elite is near entirely vanilla. ;-) (I have more esoteric layouts for other games) For me one of the best features of the Elite [pad] is simply never, ever having to use stick-clicks again. I have all four paddles fitted (a carry over from a different game I was playing), but for Elite since December I've simply mapped the left pair to flight mode toggle, and the rights to toggle free-look. I simply like having a very large surface area to effortlessly toggle both, as however I'm holding the pad or whatever I'm doing in the game, those two functions are always just a feather pull away.
Is it a set-up I'd recommend to other pilots? Nope! But I've gotten used to it. I likely will try out binding the throttle down there, but I've gotten so used to using the bumpers.
Oh, and try the two tallest sticks for the maximum control on both actions, and adjust the curves yourself in the Xbox Accessories app to fine tune performance - remember to toggle radial calculations on, as well. I change sticks almost per game; for general 3rdP adventure/action games I use the shortest left with the medium right - jabbing forward to move in such games rarely requires finesse, but camera control always benefits from accuracy and smoothness. Different sensitivity settings will affect different games in--- well, different ways. ;-) Feel free to experiment, as diving back and forth from the app to a game is effortless.
F'instance, if you have a layout you like but wouldn't mind tinkering with - but don't wish to have to 'fix' it if it doesn't improve performance - you can duplicate that layout, fiddle with the bindings/settings, and then load that to Slot 2 on the pad - that means you can have the layout which you've been using, and the tweaked layout to directly compare them on the fly as you play. All it takes is that flip of the switch in realtime.
I've been gaming since the mid/late '80's, and the Elite pad's genuinely one of the best purchases I've ever made. For action games, it almost gives a mouse-like advantage, e.g. continuing to operate the camera for situational awareness in shooters, whilst reloading or making some other action. Whilst the normal pad forces players to take their thumb off the right stick to jab X or wotnot, Elite users can keep moving, keep looking, and keep reloading/sprinting/whatever.
One negative is that after you get used to it, conventional pads just feel awful... 'What do you mean I can't change the sticks, lock the triggers, and don't have a paddle for reload?! What kind of broken thing is this!'. ;-)