You can connect both to the same U/D/R/L points, same player, on the interface if you want. No problem. Both sticks will work all the time and you can jump in and backseat drive when your kid, buddy or SO is stinking it up with lame play.
However, put the U360 on USB, it's what I did, you still will want to be able to flash it for different games unless you are hardcore classics only.