Sorry, I can't offer personal experience - I have a 6D, which has WiFi, and as Robert says isn't as reliable as cord. It's good enough for me to use professionally for architectural work, but building don't move. I don't know that I'd use it as a professional portrait photographer, but that has more to do with lag than reliability.
From what I've read on CamRanger, it's a great system, used frequently in the professional field. I was watching the videos from Mike Kelley the other day, a high-end architectural photographer, who was using the CamRanger outside of the building he was shooting in to light some palm trees. Looked impressive to me, my 6D certainly couldn't do that reliably. But, the 6D has built in wireless, the CamRanger is external which provides an antenna, and presumably is powered.
I don't know if any of this helps, before plunking down that kind of cash I'd want to hear a first hand account too. But I wouldn't compare your results with the EyeFi to a CamRanger. The EyeFi is a cheap toy, and doesn' have near the amount of control that the CamRanger allows. I would recommend going over to Canon Rumors forum. There is a much larger knowledge base over there, especially when it comes to more non-camera-centric topics like external control and lighting and whatnot.
