Newbie first post: Already down the rabbit hole; advice on UltraStik 360?

[ROMconstruct]

After a decade of dreaming about owning my own MAME cab, I've finally made the jump. I spent a couple of weeks researching, and came up with a plan: "I'll start easy and buy a cheap but functioning generic JAMMA cab. Then all I need is an ArcadeVGA and a J-PAC, and I'll be playing games in no time! Maybe start a JAMMA PCB collection on the side."

So yesterday I went to my very first arcade auction, and bought my very first cab. It's a generic JAMMA with a 25" 15KHz monitor, currently playing Soul Edge. $75 plus taxes, auction fees, and $150 to deliver it (I don't own a truck). Will probably be about $250 total cost. I'm excitedly awaiting its delivery. "I'll clean it up, sand it, paint it, replace the T-molding and any broken bits, then follow through with my plan. Should be playing games by next week!"

This morning, I started thinking more about the control panel. It's got 4 buttons per player, which doesn't support a lot of the fighting games. Well, when I bought the cab, I targeted cabs with modular control panel boxes. On many of the cabs where the CP is wider than the body, it's a separate section that can be removed for transport. I figured I could build my own custom CP box to replace the existing one. "Okay, I'll build my own CP, should be playing games in a month!"

Then I began designing my CP with 6 buttons for players 1&2. Maybe make it 4 player with 4 buttons for players 3&4. A trackball would be cool. A spinner? Dedicated 4-way? Flight stick? Oh wait, I'm already beyond the JAMMA spec with just the first sentence. "No problem. I'll ditch JAMMA, replace the J-PAC with an I-PAC 4 and a video amplifier, and I'm good to go! With the CP scope growing, I'll probably need more time to make sure I get it right. I'll be playing games by the end of summer!"

Finally, I began making a list of parts for the project. I found the UltraStik 360, which seems like it could help me simplify the CP design a lot, no more need for a dedicated 4-way or flight stick. It also connects via USB, and has an input mode so I can wire up to 8 buttons directly to each stick. I guess that means I no longer need the I-PAC 4? But I still need an Opti-PAC for the spinner and trackball, right? And maybe I still need an I-PAC to handle extra admin buttons and stuff like the coin mechs? So maybe I shouldn't use the input mode on the 360, and I should still connect it (and the buttons) to an I-PAC 4, since I may need to get the I-PAC anyway. Will all of this even work together in MAME (2/4/8 way joystick inputs via I-PAC, analog joystick input via USB)? "Oh god, I just spent $250 on a giant paperweight!"

TL;DR: If an UltraStick 360 doesn't preclude the need for an I-PAC, should you connect it to an I-PAC 4 and use the USB for analog only ("output mode"), or should you put it in "input mode" and connect the buttons to the stick instead of the I-PAC? Does one way make it easier to configure in MAME than the other? I'm asking because I'm deciding if I still need an I-PAC 4 instead of a regular I-PAC, or if I need an I-PAC at all.