Hello, I have been reading some about the new Yosemite OS, and it sounds like bluetooth 4.0 might be needed for some of the new features involving connectivity with ios. I currently have a 2011 imac, and it only has bluetooth 2.1. I can buy a dongle with bluetooth 4.0, but I am unsure if I can simply plug the new usb bluetooth in, or if it is more involved than that. Can both bluetooth devices work at the same time, or do I have to turn the internal one off and repair all my devices. Also, would this disable the keyboard commands used at startup (I use an apple bluetooth keyboard), such as the option or recovery partition? I may just have to purchase a dongle and experiment, but any one who has already tried to do this would save me a bunch of time trying to figure out how easy or hard it is to upgrade to the latest usb using a usb dongle.