You have to sign in because Razer wants you to store all your device configurations in the cloud so if you go to a friend's house and play on their computer with your device, all you have to do is sign in and download all your key maps. Would be better if it were stored on the device like the N52te.Why the heck would you have to sign in?
Not surprised, have fun trying to remove the Synaps software if you go down that road.So, I emailed Razer and asked them: "... it is fully functional for Mac? How about the software? Will I be able to customise the lighting effects?"
Their reply: "The Razer Ornata is fully functional with MAC and thanks to the Synapse Software you can fully customize it to your favor."
Going off this and what others have said here, I went and bought it. After fiddling around with the software for a while, I decide to "customize it to [my] favor". Only I can't. Chroma Configurator doesn't work with the Ornata Chroma.