The rollerball that x-arcade are releasing is going to be in its own case if I am not mistaken and will defiiniately be to big to fit in the standard x-arcade 2 player panel. You said though that you might be making your own panel and if so you could take the x-arcade rollerbal out of its box and put it into your custom panel, however I think that it might make more sense for you to just buy a happ trackballl whcih doesn't come in a box in the first place.
Personally for starters I will be going this route
http://www.geocities.com/lusosarge2000/etrackball.htmlIt is the only way to get a trackball inside the 2player controller.
I will also be adding a spinner if possible (fingers crossed)
http://www.arcadecontrols.com/arcade_X-Arcade_review.shtmlI got a oscarcontrols model 3 spinner (the only one that will fit in there)
with the usb interface and left and right mouse button harness
I will wire up the left and right mouse button harness to the Player 2 bottom 2 buttons on the xarcade, I don't know if this will cause any side effects but hopefully not.
Don't know if they will both fit in there until I try.
Any happ joysticks shoud be easy to install into the X-arcade or at least that is what I have heard.
As for the joystick quality, I think that the X-arcade uses good parts but this is a dream project that I first Imagined when I was 10 years old...good isn't good enough. I think that the competition buttons are a good investment (I am a huge fighter fan) and everyone says that they are the best for fighting games, plus I really don't like the sound of the X-arcade buttons. To be honest though I am a noob and as these parts arrive I'll see what I like and what I don't, an expensive way of doing it but really the only option for me.
Hooking up the coin door to the side buttons should be fairly simple...just a few wires. Here is a webpage that uses a more complicated setup. It should help as a guide.
http://homepage.ntlworld.com/chris.nightingale1/arcades/cbmain.htmI don't know if the Ipac can Daisy chain whith the X-arcade...would have to ask Ultimarc. Does anyone else know? That is why I thought that maybe going Ipac USB would remove any possible conflicts...Ultimarc also do an Ipac VE wich is a cheap usb ipac but may have enough features for what I have in mind.
I'll probably email Ultimarc and ask their advice.