I'm sorry - but there's no substitute for a real four way, with physical restriction on the diagonals. The U360 is a great all purpose joystick, but you can't beat being physically locked out of the corners. You get the feel, and precise control that the U360 can't quite replicate. Now, if you were to put a 4 way restrictor plate on it, it would be the same. However, that's just dumb. You completely negate all the advantages of the U360 with a 4 way restrictor plate, and paid four times what you should have for a joystick that can do the same exact thing.
In your case, I would stay with the U360, but no 4 way restrictor plate. It's a compromise, but unless you do swappable panels, that's what you have to do.