update:
Both of my cabs will power on to xBox1s running CoinOPs 4 as the primary brain. Right now, this is the only padhacks I have hooked up to the CPs. I bought a simple Component switch with 3 inputs and one output hooked up.
I have a slightly nicer version this switch thing in each of my cabinets:

For me only, I can swap out the xBox 1 for a few other items:
- I have a RGH 360 I primarily run on my tate cab for Cave schmups and Raiden. I'm currently using fightpads to play but am anxious to get them wired into my CP.
- I was given a Wii that needed a new bluetooth chip ($5) and have that hooked up to my horizontal cabinet. I'll use the wireless controllers only on them.
- I have a dreamcast at my parents house they will send out to me in a month or two when they are back for the summer. I don't think I'm going to wire it into the CP as much as I'm going to just play it with the controller.
I'm pretty sure I'm going to wire the joysticks and buttons to a DB25 connector for each player then do the 360 and xBox1 pad hacks to the other side of a DB 25. I might just put the 360 pad hacks in a project box and move it and the 360 to my horizontal cab when I want to play deathsmiles or new Street Fighters. It will be an ocean of wires and somewhat ghetto under the hood but be simple to my kids running CoinOps and flexible to my odd games likes.