So, I have a Logitech mouse (anywhere MX) that I use when traveling, and a K800/M705 keyboard/mouse combo for my desktop usage. My new rMBP is replacing both my laptop and desktop, but I haven't bought a new display yet (hoping for an ATD refresh soon), so not currently connecting it to the keyboard/mouse combo. Anyway, they all work with the help of a small unifying receiver (plugs in via USB and provides BT signal to interact with devices). My question is, now that I have a laptop with built-in BT, do I even need the unifying receiver anymore? Will all my devices pair and function through the built-in BT?