My input is likely a bit odd, but the grip in my right hand is too loose for me to manage trigger jumping (minor finger amputation'll do that, apparently). I'm pondering if there's honestly even much advantage to be had, though, considering that c-stick now just mirrors the input of the control stick anyway. I'll still c-stick some pivot smashes, but I don't use the c-stick in the air at all now (I'd only used it in melee for Ken combos anyway, as far as air useage, IIRC). I can certainly see myself spiking with it, of course, considering fast-falling nonsense, but I'm just not feeling like I'm at a disadvantage for being unable to use the triggers and the left stick simultaneously for, say, short hops and whatnot.
I have a differing setup to propose for the pro controller, and it's based loosely on what I used for the 3ds: it's optimized for slide inputs on short-hopped standards and specials:
B: Standard
Y: Special
A: Jump
X: Jump
R: Grab
ZL/ZR: Shield
R-Stick: Smash
Tap Jump Off
Both jump buttons have a purpose, in any case, as diagonal-down slide inputs are far easier this way for either attack button, while A makes for the closest button, making short hops as mechanically intuitive to input as possible, since you have the most leverage over the A button of any. L is unused, as I don't really feel much need for a second grab button in the ergonomics (LZ shielding is easier to input from a dash or such, but RZ shielding allows for easier teching and air dodging by freeing up the control stick). The problem with trigger-jumping is that it creates an inability for me to share movement controls between hands-- exactly what tap jump screwed me over with so often in melee. Simultaneous inputs on the same side of the controller just don't feel to have the same response time. Bumper jump is a long-known trick for pulling off right stick manuverability in FPSes, actually, but the question here becomes is that a necessary parallel? I can rest the crook of my thumb atop the R-stick to retreating Fair with it or the like after an X shorthop, or I can bring down my index finger to mash down on it for a spike if need be, really, but you're trading grip control for that lessened thumb movement, which means you need to alternate your grip between right and left hands on the controller at different moments. Too firm with the left and you mess up a short hop, too firm with the right and you lose response time on grabs and shields. Just keep in mind that face-button grabbing is manditory for trigger-hopping setups, as a result. Even so, it's a tradeoff between what you want finer control over: the timing and spacing of your attacks by gripping left-handedly with minimal left trigger controls, or gripping right-handedly with no 'finesse' controls mapped to right (i.e. short hop).
As a simple test, try controlling yourself with a trigger-jumping moveset without holding onto the right side of your controller-- the moment you put the burden of carrying on the left hand, the control method rather falls apart. Now, in a conventional setup, short-hopping is still affected by a right-hand-only test in the same manner, but the question is of how many buttons you'd rather impede your reactions with. The sticks are important, sure, but that means jack if you're inputting terrible tilts or can't even fire Fox's laser without pause from laying into the button too firmly with your grip-hand. The reason it works for FPSes is because the face buttons are not important during combat. It will certainly still work for granting you better stick-only-air-games, if that's what you're into, but don't forget that you're sacrificing a small bit of finesse with your right triggers and face buttons as a result. You might argue that the extra control of the L-stick would equalize that, but needing to use your trigger fingers for light-touch inputs like a trigger short hop during dashes and the like feels like a trade, not strictly haggling a flatly better control of things.
Of course, I can hardly present a non-biased stance when I've got a minor physical handicap all but preventing me from using the trigger-jump effectively, granted, but I felt it worth mentioning just on the basis that I feel like most players are apt to take their grip for granted, and mightn't realize what that may affect. Dividing work between right and left hands is certainly as important as in a PC game, but if hotkeys on the side of a mouse keep you from clicking as accurately, the tradeoff's rarely worth freeing up one's left. Feel free to take my words with a grain of salt, but I imagine that situations where your lost control becomes evident may crop up. I can't test any myself, mind you, but if someone could test tricky, face-button-stressing techs that might exist, comparing the grips would certainly be informative.
Right or left 'gripping' might, by the by, turn out to be like inverted or not-inverted controls, for the record, in that some minority ends up favoring one or the other to no tangible disadvantage or such. Honestly, though, the way the C-sticking of S4 works has me skeptical, to say the least.