USB3 is known to mess with Bluetooth reception: here and here. I just had to move my USB hub so as to get non jittery magic mouse performance. It'd be nice to be able to see when this is a problem, instead of spending time looking for imaginary cat hairs blocking the mouse lens. Apple's Wireless Diagnostics (hold down the option key, then click on the Wi-Fi icon in the menu bar) provides a nice graph, including S/N ratio for Wi-Fi, but I'm not finding similar for Bluetooth connections. Something inside the Mac is reading the transmission, surely someone has written a little App so I can see what that signal looks like? It'd be nice to find out for sure that all I have to do to decrease noise by 20 dB is wrap my hub in aluminum foil, or re-orient the SSD enclosure, instead of playing the "hey that seemed to work game.