Basically, it'd be nice to have DirectInput controller output support, as DirectInput controllers natively support 128 boolean buttons, 8 float/decimal/fractional axes, and a full-range POV (according to Wikipedia), while X-Input controllers only natively support 10 boolean buttons, 4 float/decimal/fractional axes (and 2 float/decimal/fraction triggers, so kind of 6 axes), and a single 8-way directional pad. Plus Windows can sort of have theoretically infinite DirectInput controllers hooked up, while only 4 X-input controllers, I think.
For context: Dolphin is an amazing Wii (and GameCube) emulator, and I would like to be able to hook up everything of a DualShock 4 to be usable for emulated controllers (the Wii remote and Nunchuck are motion-sensitive and such), which means I currently would have to use an X-Input controller for the common things of a DualShock 4, and then an extra X-Input controller for the individual X/Y/Z rotation and the combined X/Y/Z movement (taking up all 4 available axes), and then another X-Input controller where the touchpad "touch" 1 and 2 and the touchpad press are hooked to buttons, and the touchpad "touch" 1 and 2 X and Y are mapped to the left and right stick's X and Y axes, respectively.
This effectively means I have to use three X-Input controller outputs in order to get all the mappings of a DualShock 4 visible for Dolphin, since it uses the standard DirectInput (and X-Input), not natively supporting the extra things of the DualShock 4's touchpad and gyroscope, where-as I could use a single X-Input output and a single DirectInput output to get everything I want visible for Dolphin. (Yes, Dolphin lets you use multiple controllers for controller mapping, not just one.) I might not even be able to hook up just two DualShock 4's to Dolphin if I want to map them to three X-Input controllers each. And no, using the keyboard or mouse output plug-ins don't count, as I want them to be free for chatting with friends and such online while playing. (Yes, I'm using the InputMapper 2.0 beta.)
So in summary: 128-button, 8-axis, 1-POV DirectInput output support would be amazing.
Well, just know that you can't fully expose a DualShock 4 like this with a single DirectInput output, as a DualShock 4 has too many axes for that, and I'm also hoping to be able to set it up manually to set each input to exactly the output I want.
The optimal output option would probably be 1 X-Input controller for the common things (as well as getting rumble support) and 1 DirectInput controller for the special things, which should then leave out either the "touch" 2 X/Y axes, or the independant X/Y/Z movement axes (rather than X/Y/Z movement combined into one axis).
It might be better off as a plug-in for InputMapper 2.0 than a built-in feature of InputMapper 1.X (though both would probably be best), however I'm not quite sure how it'd work in InputMapper 1.X for my intentions.
Nope, there's not. DirectInput itself is limited to 8 axes. (So optimally, the sticks and triggers would go on an X-Input output, while the gyroscope X/Y/Z, movement X/Y/Z, and touchpad touch 1 X/Y, totalling 8 axes, would go on a DirectInput output (along with touchpad press-down and touchpad touch 1/2 "buttons" also being mapped to the DirectInput output).)