if i am correct about the u360 being the same as a sanwa JLW, then they should fit. i have never used a JLW stick, so i dont know how they feel, or how they switch from 8 to 4 way..but i would guess it is by rotating a restrictor plate on the bottom of the joystick.
the only top switchable sticks that i know of are the magstik plus, and the omnistick prodigy..neither of which will mount right in the same holes as an x-arcade stick
as for how the u360 works in 4way mode..it doesn't ignore the diagonals...it just tells the pc that it is a different direction...you program it with a map like this:

so if you push up, then rotate teh stick around to the right, it will still send the up signal until you cross the 45degree mark, then it goes instantly to Right...that way there are no dead spots...like you would get when you put an xarcade stick in 4way mode.